Cheddar Summer Squash Casserole with Fresh Thyme
A comforting baked casserole featuring tender yellow summer squash layered with sharp cheddar cheese, fresh thyme, and cubed bread in a rich custard base. The squash is first sauteed with sweet onions until lightly caramelized, then combined with beaten eggs and half-and-half to create a creamy texture. Perfect for summer gatherings when squash is abundant, this dish works beautifully as a side for grilled meats or as a vegetarian main course. The combination of sharp cheddar and aromatic fresh thyme gives it a sophisticated flavor profile that transforms humble summer vegetables into something special.
Ingredients
- 2 tablespoons butter or margarine
- 1 medium sweet onion, chopped (1/2 cup)
- 4 yellow summer squash (1 1/4 lb), cut into 1/4-inch slices
- 2 eggs
- ½ cup half-and-halfwhole milk1:1lower-fatadds dairy
Slightly less rich but still creamy
- 1 ¼ cups shredded sharp Cheddar cheese (5 oz)
- 2 teaspoons fresh thyme leaves
- ½ teaspoon salt
- ¼ teaspoon freshly ground pepper
- 2 cups hearty white bread, cubed (1 inch)
- fresh thyme sprig
Instructions
- 1
Heat oven to 375°F and generously spray 8-inch square glass baking dish with cooking spray
- 2
Melt butter in 12-inch skillet over medium-high heat
- 3
Cook onion in butter 2 minutes, stirring frequently, until almost tender
- 4
Add squash and cook 4 minutes, stirring occasionally, until just tender and lightly browned
- 5
Remove from heat and cool 5 minutes
- 6
Beat eggs with whisk in large bowl until blended
- 7
Stir in half-and-half, 3/4 cup cheese, thyme leaves, salt and pepper
- 8
Gently stir in squash mixture and bread cubes
- 9
Spoon into prepared baking dish
- 10
Bake uncovered 20 minutes
- 11
Top with remaining 1/2 cup cheese and bake 10 minutes longer or until puffed and golden
- 12
Let stand 10 minutes before serving and garnish with thyme sprig
Tips
Let the sauteed squash cool for the full 5 minutes before mixing with eggs to prevent curdling the custard base.
Use day-old bread for the best texture - fresh bread can become too soggy while stale bread holds its shape better.
Check doneness by inserting a knife in center - it should come out mostly clean with just a few moist crumbs.
Good to Know
Refrigerate covered up to 3 days. Reheat in 350°F oven until heated through.
Can assemble up to 4 hours ahead and refrigerate. Add 5-10 minutes to baking time if cold.
Let stand 10 minutes before serving to allow custard to set properly.
Common Mistakes
Don't skip cooling the squash mixture to avoid scrambling the eggs.
Avoid overbaking or the custard will become rubbery and watery.
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I use frozen squash instead of fresh?
Thaw and drain frozen squash thoroughly, then pat dry with paper towels. Skip the sauteing step and add directly to the egg mixture since frozen squash is already partially cooked.
What if I don't have half-and-half?
Mix equal parts heavy cream and whole milk, or use just whole milk for a lighter version. Avoid skim milk as it won't provide enough richness for the custard.
How long will leftovers keep in the refrigerator?
Store covered in the refrigerator for up to 3 days. Reheat individual portions in the microwave or warm the whole dish in a 350°F oven until heated through.