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Home » Recipes » Side Dishes » Ham Mushroom and Spaghetti Squash Casserole

Ham Mushroom and Spaghetti Squash Casserole

October 3, 2023 by Lori V Leave a Comment
Disclosure: This post may contain Amazon or other affiliate links. As an Amazon Associate, I may earn a commission from qualifying purchases. This does not change your price should you buy something.

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In case you’re not already on the “spaghetti squash” is awesome train, let me tell you that it is amazingly delicious and versatile in terms of flavors it can complement.  You can spice it up, sweeten it up, cheese it up, and so on.  In this Ham Mushroom and Spaghetti Squash Casserole, we combine tender spaghetti squash, savory ham, earthy mushrooms, nutritious spinach and melted cheese.  Awesome as a side or a vegetarian main, this casserole makes a great addition to any dinner party or weekly meal plan.  

Ham Mushroom and Spaghetti Squash Casserole - finished and in a bowl

What You Need to Make Ham Mushroom and Spaghetti Squash Casserole

Equipment

  • Rimmed Baking Sheet – This is just for roasting the spaghetti squash.  I cover mine with aluminum foil first.  
  • Aluminum Foil
  • Chef’s Knife
  • Cutting Board
  • Spoon – For spooning the “guts” out of the spaghetti squash.  
  • Fork – For shredding the spaghetti squash.  
  • Large Sauté Pan or Skillethttps://amzn.to/3F2fiOE
  • Stirring Utensil
  • Measuring Spoons
  • Measuring Cups
  • Large Mixing Bowl
  • 9×13 inch Casserole Dish
  • Cooking Spray

Ingredients

  • Large Spaghetti Squash – If you can’t find a large one, use 2 smaller ones. 
  • Kosher Salt
  • Ground Black Pepper
  • Dried Ground Mustard
  • Paprika – You can use either sweet or smoked paprika for this recipe.  I usually use smoked. 
  • Chipotle Powder – If you have guests who are strictly anti-spice, you can skip the chipotle powder.  However, it really does provide some nice flavor depth to the dish.  
  • Onion Powder
  • Garlic Powder
  • Onion
  • Spinach – I used fresh spinach for this recipe.  
  • Ham
  • Mushrooms – You can use either Baby Bella or White Button mushrooms for this recipe. 
  • Salted Butter – You can use unsalted butter if you prefer.  
  • Heavy Cream
  • Parmesan – I used grated Parmesan for convenience.
  • Shredded Cheddar – You can either buy pre-shredded or shred it yourself.  I use pre-shredded cheddar.  Just be aware that the anti-caking agent found in many pre-shredded cheeses adds about 1 gram of carbs per ¼ cup.  

Getting Started with Making Ham Mushroom and Spaghetti Squash Casserole

Ham Mushroom and Spaghetti Squash Ingredients Labeled

Preparing the Spaghetti Squash

Start by lining a rimmed baking sheet with aluminum foil and preheating the oven to 400°F.  With a sharp knife, you’ll poke a few slices / holes into all sides of the spaghetti squash.  Then roast the spaghetti squash at 400°F for 20 minutes, turn it over, then roast it for 20 minutes longer.  After that, you can remove the spaghetti squash from the oven and allow it to cool until it is comfortable to handle.  Slicing it in half lengthwise, you’ll carve out the slimy “guts” and seeds with a spoon.  Once removed, you’ll want to use a fork to shred the flesh of the squash into “spaghetti-like” strands.  Set it aside.  You can prep up through this step in advance and then just store it in the fridge until you’re ready to use it.

Chopping and Pre-Cooking

Next we’ll get to chopping and pre-cooking.  I dice the onions, chop the spinach, slice the mushrooms, and dice the ham.  

Because I like the flavor of salted butter and mushrooms, I heat 2 tablespoons of salted butter over medium high heat and then add the mushrooms.  You’ll want to cook the mushrooms until they release their juices.  Spoon them into a bowl and set them aside.  

Chopped raw spinach
Sliced and cooked Baby Bella mushrooms

To the same pan, we’ll then add the chopped onions and spinach.  Add more butter or avocado oil or olive oil if needed for cooking.  For me, the residual mushroom juices and butter are usually enough liquid. Sauté the onions and spinach until the onions are softened and the spinach is wilted.  Once done, remove them from the heat and set them aside. 

If you didn’t buy ham that is already cubed or diced, go ahead and dice it.  Then set it aside.

Cooked Spinach and Chopped Onions
Diced Ham

Combining All Components

For better distribution of the spices, we’re going to mix the spices together and then into the heavy cream.  That allows us to take advantage of the liquid for distribution of seasoning throughout the dish.  

Mixed spices for Ham Mushroom and Spaghetti Squash Casserole
Heavy Cream and spices whisked together in a measuring cup

Because spaghetti squash has a tendency to clump a bit, I like to combine the components of this casserole in stages.  In a large mixing bowl, add about a third of each of the following: spaghetti squash, mushrooms, the onion and spinach mixture, the ham, each cheese, and the spiced heavy cream.  Repeat that process until all of the components have been incorporated.  Stir until everything is evenly distributed.  

Baking the Casserole

Preheat the oven to 350°F and spray a 9×13-inch casserole dish with cooking spray.  Pour the casserole mixture into the dish and bake at 350°F for 30 minutes or until heated through.  If you would like to add some cheesiness, after 20 minutes, sprinkle a cup of shredded cheese on top of the casserole and then finish baking it.  You can use more shredded cheddar or a Mexican cheese blend or some other cheese of your choice.  

Serve warm.  If you need to keep this warm while finishing up other items, stick it back in the oven on Warm (180°F).  If you’re going to have it in the oven on Warm for more than 20 minutes, cover it with aluminum foil first.  

Related Recipes

If you’re interested in another spaghetti squash recipe, check out my Creamy Garlic, Broccoli, and Mushroom Spaghetti Squash.  

Wondering what else to serve with this Ham Mushroom and Spaghetti Squash Casserole, check out my Fall Kickoff Dinner Party post for some menu ideas.

Ham Mushroom and Spaghetti Squash - Finished Close up

Ham Mushroom and Spaghetti Squash Casserole

Indulge in the ultimate comfort food with this Ham Mushroom and Spaghetti Squash Casserole recipe! With tender spaghetti squash, savory ham, earthy mushrooms, nutritious spinach and melted cheese, this dish is a flavor explosion in every bite. Perfect for serving to guests at your next dinner party or as a make-ahead weeknight meal. Don’t wait, try this mouthwatering recipe now!
Print Pin Rate Add to Menu Go to Dinner Party Menus
Course: Main Course, Side Dish
Cuisine: American
Keyword: Keto, Vegetables, Vegetarian
Prep Time: 30 minutes minutes
Cook Time: 1 hour hour 20 minutes minutes
Total Time: 1 hour hour 50 minutes minutes
Servings: 10
Calories: 251kcal

Ingredients

  • 1 Large Spaghetti Squash
  • 1 teaspoon Kosher Salt
  • 1 teaspoon Ground Black Pepper
  • ½ tablespoon Ground Mustard
  • ½ tablespoon Paprika
  • ½ teaspoon Chipotle Powder
  • ½ teaspoon Onion Powder
  • ½ teaspoon Garlic Powder
  • ½ Large Onion Chopped
  • 10 ounces Spinach Chopped
  • 8 ounces Ham Diced
  • 12 ounces Mushrooms Sliced and cooked
  • 2 tablespoons Salted Butter
  • ½ cup Heavy Cream
  • ¼ cup Parmesan Shredded or Grated (~1 ounces, ~27 grams)
  • ¾ cup Cheddar Shredded (2.5 ounces, 72 grams)
  • 1 cup Mexican Cheese Blend Optional for topping. Shredded. Or another cheese of your choice.
Prevent your screen from going dark

Instructions

  • Line a rimmed baking sheet with aluminum foil and preheat the oven to 400°F. Using a sharp knife poke a few slices / holes into all sides of 1 Large Spaghetti Squash. Roast the spaghetti squash at 400°F for 20 minutes, turn it over, then roast it for 20 minutes longer.
    1 Large Spaghetti Squash
  • After removing the spaghetti squash from the oven, allow it to cool until it is comfortable to handle. Then slice it in half lengthwise, use a spoon to carve out the slimy “guts” and seeds. Once removed, use a fork to shred the flesh of the squash. Set it aside. You can prep up through this step in advance and then just store it in the fridge until you’re ready to use it.
    1 Large Spaghetti Squash
  • Mix the spices–1 teaspoon Kosher Salt, 1 teaspoon Ground Black Pepper, 1/2 tablespoon Ground Mustard, 1/2 tablespoon Paprika, 1/2 teaspoon Chipotle Powder, 1/2 teaspoon Onion Powder, and 1/2 teaspoon Garlic Powder–and set them aside.
    1 teaspoon Kosher Salt, 1 teaspoon Ground Black Pepper, 1/2 tablespoon Ground Mustard, 1/2 tablespoon Paprika, 1/2 teaspoon Chipotle Powder, 1/2 teaspoon Onion Powder, 1/2 teaspoon Garlic Powder
  • Dice 1/2 Large Onion and 8 ounces Ham, slice 12 ounces Mushrooms, and chop 10 ounces Spinach.
    1/2 Large Onion, 10 ounces Spinach, 8 ounces Ham, 12 ounces Mushrooms
  • Heat 2 tablespoons Salted Butter in a large sauté pan over medium high heat. Cook the mushrooms until they release their juices. About 6 – 8 minutes. Remove from the heat and set aside.
    2 tablespoons Salted Butter, 12 ounces Mushrooms
    Sliced and cooked Baby Bella mushrooms
  • In the same pan, cook the onions and spinach until the onions have softened and the spinach is wilted. About 8 – 10 minutes. Remove from the heat and set aside.
    1/2 Large Onion, 10 ounces Spinach
    Cooked Spinach and Chopped Onions
  • Mix the spices with ½ cup Heavy Cream and whisk to combine.
    ½ cup Heavy Cream
    Heavy Cream whisked with spices
  • In a large mixing bowl, combine the spaghetti squash, mushrooms, ham, onions, spinach, heavy cream with spices, 1/4 cup Parmesan, and 3/4 cup Cheddar Stir until well combined.
    1/4 cup Parmesan, 3/4 cup Cheddar
  • Pour the mixture into a greased 9×13-in casserole dish. If preparing this casserole in advance, you can pause at this step and store it in the refrigerator until ready to bake.
  • Bake the casserole in the oven at 350°F for 30 minutes or until heated through and the cheese is melted.
  • As an optional addition, sprinkle 1 cup Mexican Cheese Blend (or other shredded cheese of your choice) on top of the casserole for the last 10 minutes of baking.
    1 cup Mexican Cheese Blend
    Ham Mushroom and Spaghetti Squash Casserole after adding shredded cheese on top
  • Serve warm.

Equipment

  • Rimmed Baking Sheet
  • Aluminum Foil
  • Chef's Knife
  • Cutting Board
  • Fork
  • Spoon
  • Large Sauté Pan or Skillet
  • Stirring Utensil
  • Measuring Spoons
  • Measuring Cups
  • Large Mixing Bowl
  • 9 x 13 inch Casserole Dish

Your Own Recipe Notes

Made this recipe with your own special twist? Click here to add your own private notes.

Nutrition

Nutrition Facts
Ham Mushroom and Spaghetti Squash Casserole
Amount per Serving
Calories
251
% Daily Value*
Fat
 
18
g
28
%
Saturated Fat
 
10
g
63
%
Trans Fat
 
0.1
g
Polyunsaturated Fat
 
1
g
Monounsaturated Fat
 
5
g
Cholesterol
 
54
mg
18
%
Sodium
 
729
mg
32
%
Potassium
 
492
mg
14
%
Carbohydrates
 
11
g
4
%
Fiber
 
3
g
13
%
Sugar
 
4
g
4
%
Protein
 
14
g
28
%
Vitamin A
 
3401
IU
68
%
Vitamin C
 
11
mg
13
%
Calcium
 
230
mg
23
%
Iron
 
2
mg
11
%
* Percent Daily Values are based on a 2000 calorie diet.
Tried this recipe?Let us know how it was!

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