This cheesy baked Zucchini Casserole is out of this world amazing!
I think it goes without saying that I’m perpetually on a zucchini kick. I’m always finding new ways to cook it and love it every which way I’ve tried it!
Some of my favorite uses for this gorgeous green squash include spiralizing it into a piping hot bowl of chicken zoodle soup or baking it with lemon, basil and feta in my hasselback zucchini recipe.
Today I gave it the gold star treatment and went full-on cold weather casserole with it using the caramelized onion cream sauce from my broccoli, cauliflower, and brussels sprout gratin.
Hellooooo match made in heaven!
As written, this rockin’ recipe yields approx. 8 side dish sized servings.
Need a smaller serving? If you’re not big on leftovers, feel free to halve the recipe to make a side-dish worthy serving to scarf in a sitting.
Baked Zucchini Casserole
We love this easy cheesy vegetarian side dish!
- 1 lb zucchini squash
- 2 cups finely diced onion
- 1 tsp olive oil
- 3 TBSP butter
- 3 TBSP all-purpose flour
- 3/4 cup milk (warmed via microwave or stovetop)
- 1/4 tsp salt plus extra as needed/desired
- 1/4 tsp black pepper plus extra to taste
- 1/4 tsp garlic powder
- 1/8 tsp ground nutmeg
- 4 oz freshly grated Gruyere cheese
- 4 oz freshly grated Gouda cheese
Crispy Italian Breadcrumb Topping
- 1/2 cup Italian seasoned breadcrumbs (panko or regular)
- 1 TBSP unsalted butter
- Measure out all your ingredients, this will come in handy as the sauce comes together fast!
- Discard the ends, then slice each zuchini into 1/4-inch discs. Take care not to slice them too thin or they will get too soft/mushy while cooking. If bite-sized forkfuls are preferred, feel free to cut the rounds in half lenghtwise.
- Sprinkle zucchini slices with sea salt and place on an absorbent (clean) dish towel. Allow to sit a minimum of 15 minutes, though 30-40 minutes will help draw out more water. You'll notice water droplets on top of the slices when this happens. Pat dry on both sides using paper towels to remove as much moisture as possible. No one likes soggy squash!
- Preheat oven to 375°F
- Heat a medium pot to medium-high heat with 1 tsp olive oil. Sauté onions, stirring occasionally. Continue cooking until onions are golden brown and tender.
- Move onions to the side (if possible) and add 3 TBSP butter. Once melted, add the flour, whisking with a metal whisk constantly for 2 minutes while it bubbles and darkens in color. This roux will thicken the sauce. Pour heated milk into the butter-flour mixture and whisk well. Bring to a light boil, whisking constantly for 1 minute or until the mixture has thickened.
- Remove from heat and add salt, pepper, garlic powder, and nutmeg. Working in 2-3 batches, add half the Gruyere cheese and all of the Gouda cheese, whisking in between each batch to gently melt the cheese.
- Arrange zucchini in a medium baking dish and top with your sauce. Sprinkle with remaining gruyere cheese. Bake at 375°F for approx. 20-25 minutes, until the top is golden brown and the zucchini has reached ideal tenderness.
- While the casserole bakes, add Italian-seasoned breadcrumbs to a heated pan/skillet with butter and gently toast until golden. Carefully sprinkle over casserole once ready and finish remaining bake time.
- Enjoy hot!
If you get a chance to try this cheesy baked zucchini casserole, let me know!
Leave some love in the comment form below or tag your photos with @peasandcrayons on Instagram so I can happy dance over your creation. I can’t wait to see what you whip up!
have a few extra zucchini to use up?
Whip up this vegetarian Zucchini Parmesan for dinner tonight! These crispy zucchini rounds can be served over zoodles or noodles with your favorite spaghetti sauce for dinner or serve them straight up in a bowl with marinara sauce for dunking and make it an app!
My easy cheesy Hasselback Zucchini Pizzas are always a hit with kids and adults!
An all-time favorite of mine, these zucchini studded Veggie Burgers are crazy good an easy to meal prep. Store some in the fridge for a fast weeknight dinner and tuck a few away in the freezer for later!
Everyone absolutely loved your zucchini casserole recipe. Thank you for sharing! It was amazing and I’ll be making it in the future for sure.
Sooo good- and perfect for Lent. Have you ever considered using mozz? Curious how it would taste.
Mozzarella would be amazing!
My family loves zucchini, so I can’t wait to try this! Thanks so much for sharing the recipe!
So excited for y’all to try it! Thanks Jessica!