Ground Beef Zucchini Casserole

Ground beef zucchini casserole is a tasty, filling, and healthy dish that layers seasoned ground beef with tender zucchini slices, fresh tomatoes, and plenty of gooey cheese. It’s an ideal low-carb meal for hectic weeknights or prepping ahead, and it’s loved by the whole family for good reason.

Right now, zucchini are everywhere, and life feels busier than ever. This ground beef zucchini casserole is a wonderful way to use up all that fresh summer squash while putting a wholesome, delicious meal on the table without a ton of effort.

Casseroles have earned their place in our kitchens because they’re usually straightforward, made from simple ingredients, and don’t require a lot of hands-on time.

With summer zucchini ready to be enjoyed and busy evenings ahead, this ground beef zucchini casserole is a lifesaver for weeknight dinners. It stacks flavorful ground beef cooked with simple seasonings and juicy drained tomatoes in between layers of salted zucchini slices and loads of melty mozzarella. It’s like a lighter version of lasagna but comes together so much quicker and easier.

Throughout this post, I’ll share a short list of ingredients—only six main ones plus your pantry basics—step-by-step photos to guide you, and an easy assembly process that takes just minutes before it goes into the oven. I’ll also share my best tips, like salting zucchini to keep things from getting soggy, ideas for variations, tips on storing and reheating, plus a handy printable recipe card at the bottom so you can get cooking without delay.

Why You’ll Love It

• Simple ingredients. This ground beef zucchini casserole calls for just six straightforward ingredients (besides the usual seasonings) that you likely have in your kitchen already.
• Easy to make. It’s quick to throw together, which means less stress after a long day and more time around the table with your family.
• Meal prep friendly. This dish stores well in the fridge for several days and reheats perfectly, making it a great option to batch cook.
• Budget friendly. Ground beef is an affordable source of protein, and zucchini plentiful in the summer means this dish is kind to your wallet.
• Nutritious. Similar to lasagna but without the pasta, this casserole packs plenty of veggies and protein while staying low carb and gluten-free—try our ground turkey zucchini casserole if you want a lighter variation.
• Delicious. Above all else, it’s loaded with comforting, cheesy, savory goodness that even picky eaters will enjoy. For another kid-friendly way to use zucchini, try zucchini breadsticks for kids.

Ingredient Checklist

• 2 medium zucchini, about 2 pounds, sliced into rounds
• 1 tablespoon olive oil
• 1 small onion, diced
• 2 garlic cloves, minced
• 1 pound lean ground beef
• 2 teaspoons Italian seasoning
• ½ teaspoon kosher salt
• ½ teaspoon black pepper
• 1 28-ounce can diced tomatoes, drained
• 2 cups shredded mozzarella cheese

How to Assemble and Bake

1. Slice the zucchini into about ½-inch rounds and toss the slices with salt in a colander or sieve set over a bowl or the sink.
2. Let the salted zucchini sit for 15 minutes to release excess moisture.
3. Rinse the zucchini slices well under cold water to remove the salt, then pat them dry with paper towels.
4. Drain the canned diced tomatoes well.
5. Heat the olive oil in a large skillet over medium-high heat.
6. Add the diced onion and cook until softened, about 2 minutes.
7. Add the minced garlic and ground beef, break up the meat, and cook, stirring often, until fully browned (about 5 minutes).
8. Drain excess fat from the skillet if necessary.

9. Stir in the drained diced tomatoes, Italian seasoning, kosher salt, and black pepper, then remove the skillet from the heat.

   

10. Preheat the oven to 350°F (175°C).
11. Spread half the meat mixture in an 8×8-inch baking dish.
12. Layer half the zucchini slices over the meat mixture and sprinkle half the shredded mozzarella on top.
13. Repeat the layers with the remaining meat mixture, zucchini slices, and mozzarella.
14. Bake for 20 to 25 minutes, until the cheese is melted and starting to turn golden brown.
15. Let the casserole rest for 10 minutes before slicing.

Tips for Perfect Texture

Salt the zucchini. This step is key. Zucchini hold a lot of water, and without salting, your casserole might be watery. Salting brings out excess moisture so the zucchini bakes up beautifully without being soggy. For more moisture-control techniques, see how to roast zucchini for crisp, non-soggy results.

Baking pan. An 8×8 pan helps keep the casserole thicker with nice deep layers. You can use a 9×13 pan if that’s what you have, but the casserole will be flatter and might cook a bit faster.

Make ahead. Feel free to prep the meat mixture, slice and salt zucchini, and shred cheese earlier in the day or the day before. Just assemble right before baking for the best texture.

Let it rest. Resting the casserole for 10 minutes after baking makes it easier to cut and serve without it falling apart.

Storage. Keep leftovers refrigerated in an airtight container for 3–4 days. Warm them gently in the microwave or oven.

Freezing. I don’t recommend freezing this dish because the zucchini tends to release water and get mushy.

Flavor and Ingredient Swaps

• Meat: Swap the ground beef for ground turkey (a high-protein ground turkey casserole), chicken, or even a plant-based ground meat if you prefer.
• Cheese: To vary things, swap one mozzarella layer for ricotta or cottage cheese to make it taste more like classic lasagna (see our Mushroom and Spinach Lasagna for a ricotta-forward example). Parmesan sprinkled on top adds a lovely savory finish.
• Vegetables: Mix in baby spinach, sliced mushrooms, or even yellow squash for extra flavor and nutrition. You can also use sliced eggplant either alongside or instead of zucchini—just salt those slices first too.
• Seasonings: My favorite homemade Italian blend is perfect here, but if you don’t have it on hand, dried oregano, basil, and thyme work beautifully too.

Storage and Reheating Tips

Refrigerate: Let the casserole cool completely, then transfer leftovers to an airtight container and keep in the fridge for 3 to 4 days. For easy meal prep, consider storing individual portions in smaller containers.

Reheating tips:

• Oven (best texture): Preheat to 350°F (175°C). Place a portion in an oven-safe dish, add a splash of water or extra tomato juice if it seems dry, cover with foil, and warm for 15–20 minutes until heated through.
• Microwave (fast): Put a serving on a microwave-safe plate, cover with a lid or damp paper towel to hold in moisture, and heat for 1–3 minutes, stirring or rotating halfway to ensure even warming.

Make-ahead: You can prep the meat mixture, slice and salt zucchini, and shred cheese 1 or 2 days beforehand. While assembling just before baking gives the best result, you can assemble ahead, cover tightly, and refrigerate unbaked for up to 24 hours—though expect a bit more moisture from zucchini. The same make-ahead approach works well for a Mediterranean-style alternative like this Savory Mediterranean Chicken Zucchini Bake.

Freezing (not ideal): Zucchini’s high water content means freezer storage changes the texture and makes the casserole watery. If you must freeze, cool completely, pack into a freezer-safe container or wrapped tightly in foil, remove extra air, and freeze for up to 2 months. Thaw in the fridge overnight and reheat covered in a 350°F oven. Be prepared for some softness in the veggies and cheese, though. If you’d rather stock the freezer with something that freezes cleanly, consider a batch of Creamy Lentil Curry with Coconut Milk.

Answers to Common Questions

• Can I use other meats? Absolutely! Ground turkey, chicken, or Italian sausage all work well here. If you like the chicken-and-zucchini combo, our Ground Chicken Zucchini Rice Skillet offers a quick, similar weeknight option. Just adjust seasonings and drain any excess grease if your meat is fattier.
• Can I make this vegetarian? You can! Try swapping the beef for cooked lentils, crumbled firm tofu, tempeh, or a plant-based ground meat. For another hearty meatless dinner idea, see Lentil Mushroom Stroganoff for rich, savory lentil flavor. You might want to add extra herbs or a bit of tomato paste to boost flavor.
• How do I avoid a soggy casserole? Salting zucchini to pull out water and rinsing it thoroughly is crucial. Also, drain canned tomatoes well, and use a smaller 8×8 pan to keep layers deep and reduce watery runoff.
• Is this recipe gluten-free? Yes! No wheat ingredients here. Just check any cheese or meat substitutes you use to ensure they don’t contain hidden gluten.
• How do I know when it’s done? Bake the casserole at 350°F for 20–25 minutes until the cheese is melted and turning golden. Let it rest 10 minutes to set before slicing.
• Can I double the recipe? Definitely. Use a bigger pan like a 9×13 and spread the casserole in a single layer. Watch the bake time closely—it might need less time to cook through and get bubbly.