Hello Zucchini Lovers! Whether you grabbed some zucchini from the farmers’ market, have some in your fridge that you want to use up, or have a bunch growing in your garden, this recipe is for you!

This recipe is perfect for when you have an abundance of zucchini. You can even prep your summer zucchini for winter casseroles by freezing it when it is ripe and ready for eating. Anyway you slice it, this is one of my favorite casserole recipes featuring tender zucchini.

I make this casserole extra special with a homemade walnut breadcrumb topping made with leftover crusty bakery bread and I serve it all with a whipped herbed cottage cheese sauce for extra creaminess and freshness. This recipe is soon to be your favorite zucchini recipe.

Veggie Packed: This recipe is loaded with zucchini and mushrooms

Cheesy: This recipe has creamy cottage cheese and sharp and creamy parmesean cheese, adding to the decant flavors of the dish.

Whole Foods: You know all the foods in this recipe.

Easy Recipe: This Easy zucchini casserole  recipe is perfect as an easy side dish to compliment a main protein like grilled chicken thighs, baked fish, or air fryer tofu.

Versatile: keep this 100% vegetarian or add some ground chicken or turkey to the mushroom sauté before the bake for even more of a protein punch.

Special Touches
Meal Prep Friendly- this is there perfect side dish to make in advance for busy weeknights.

Zucchini Slices: Sliced thin with a mandolin, but you could use a sharp knife
Sautéed Mushrooms: Sliced and sauteed in a good-quality olive oil
Cream sauce base: With ingredients such as cottage cheese, milk, eggs, parmesan cheese, and olive oil, this cream sauce is truly luxurious while adding bulk to the recipe.
Bread Crumb Topping: This sends this recipe over the top. Making your own homemade breadcrumb walnut topping makes this casserole extra special.
Whipped Herb Cottage Cheese Sauce to Finish: This adds a boost of freshness that visually looks amazing, but also tastes fantastic paired with the zucchini and mushrooms.

Prep the pan & zucchini

• • Heat oven to 375°F (190°C). Lightly oil a 9×9 baking dish.

  • Slice 2 medium zucchini into thin rounds.

  • Tip (avoid watery bakes): Skip extra-large zucchini, they hold more water and taste blander. Using frozen zucchini noodles? Thaw, squeeze dry, and chop into 1–2″ lengths so they layer neatly.

Sauté the veggies

• • In a large skillet, heat 1 Tbsp olive oil.

  • Cook 1 sliced onion until golden (about 8 min). Add 3 cloves minced garlic and 8 oz sliced mushrooms; cook until the mushrooms release liquid and it evaporates and they brown (6–8 min). Season with salt/pepper.

  • Tip Moisture control: Cook until the pan looks nearly dry, this keeps the casserole from becoming too watery. 

Make the cream base

• • Whisk ¼ cup milk, ¼ cup cottage cheese, 2 eggs, ¼ cup grated Parmesan, a pinch of red pepper flakes(optional), salt, and black pepper until smooth.

Assemble

• • Layer all the zucchini in the dish.

  • Spoon the mushroom-onion mixture over top.

  • Pour the cream base evenly over the vegetables.

  • Sprinkle the remaining ¼ cup Parmesan over everything.

  • Top with ½ cup walnut breadcrumbs (your mix of fresh breadcrumbs + chopped walnuts).

  • Finish with a generous drizzle of olive oil over the crumbs.

Bake

• • Cover the dish loosely with foil and bake 20 minutes.

  • Remove foil and bake 15–20 minutes more, until the top is golden and the center is set.

  • Oven variance tip: Cooking times vary by oven, check early on in the bake. If the top browns too fast, re-cover with foil.

Rest & Finish

• Let sit 10 minutes to set.
• Shower with fresh herbs (basil, parsley, chives, thyme, or oregano).
• Serve with the Whipped Cottage Cheese Herb Sauce on the side or spooned over each portion.

Cheese: Add mozzarella cheese or sharp cheddar cheese for even more cheesiness.

Veggie addition: I use sautéed mushrooms, but you could also include bell peppers, beans, tomatoes, or corn.

Use fresh zucchini (sliced or grated), frozen zucchini (diced, spiraled).

Casserole Cream Sauce: For this sauce, I blended cottage cheese with the milk and eggs. You could use sour cream, yogurt, or heavy cream.

Breadcrumbs: You can omit the nuts in the breadcrumb recipe or could use store-bought breadcrumbs if you prefer.

Whipped Cottage Cheese Herb Sauce: For MORE flavor and protein

This recipe might be even better the next day as leftover zucchini casserole! It might sound weird but, I love to eat a slice of this at breakfast with a cup of coffee and a side of fresh fruit.