Two-Cheese Summer Squash Casserole with Parmesan Crust
A comforting baked casserole featuring tender yellow summer squash and sweet onion in a creamy mixture of sour cream, Parmesan, and Cheddar cheese. The dish is topped with buttery breadcrumbs and extra Parmesan that bakes to a golden crust. Perfect as a side dish for family dinners or potluck gatherings, this casserole transforms simple summer vegetables into a rich, satisfying dish that appeals to all ages.
Ingredients
- 4 lb yellow summer squash, sliced
- 1 large sweet onion, finely chopped (1 cup)
- 2 ½ cups soft bread crumbs
- 1 ¼ cups freshly grated Parmesan cheese, (5 oz)
- 1 container (8 oz) sour cream
- 1 cup shredded Cheddar cheese, (4 oz)
- ½ cup chopped fresh chives
- 1 teaspoon garlic salt
- 1 teaspoon freshly ground pepper
- 2 eggs, slightly beaten
- 2 tablespoons butter or margarine, melted
Instructions
- 1
Heat oven to 350°F and spray 3-quart casserole with cooking spray
- 2
Heat 4 quarts water to boiling in Dutch oven
- 3
Add squash and onion to boiling water and cook uncovered 8 minutes or just until tender
- 4
Drain squash mixture well
- 5
Stir together squash mixture, 1 cup bread crumbs, 3/4 cup Parmesan cheese, sour cream, Cheddar cheese, chives, garlic salt, pepper and eggs in large bowl
- 6
Spoon mixture into prepared casserole
- 7
Mix remaining 1 1/2 cups bread crumbs and 1/2 cup Parmesan cheese with melted butter in small bowl
- 8
Sprinkle breadcrumb mixture over squash mixture
- 9
Bake uncovered 35 to 40 minutes or until set
- 10
Let stand 5 minutes before serving
Tips
Drain the squash mixture very well after boiling to prevent a watery casserole
Let the casserole rest for 5 minutes after baking for easier slicing and serving
Use freshly grated Parmesan cheese for the best flavor and texture in the topping
Good to Know
Refrigerate leftovers for up to 3 days in covered container
Can be assembled up to 1 day ahead, cover and refrigerate, then bake as directed adding 5-10 minutes
Serve hot as a side dish with roasted meats or grilled proteins
Common Mistakes
Don't skip draining the squash well to avoid watery texture
Don't overbake or the eggs will curdle and become rubbery
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I use frozen summer squash instead of fresh?
Yes, but thaw and drain thoroughly first as frozen squash releases more water than fresh.
What if I don't have fresh chives?
Substitute with 2 tablespoons dried chives or use chopped green onions for similar flavor.
How long will this casserole keep in the refrigerator?
Properly stored, it will keep for up to 3 days covered in the refrigerator and reheats well.