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Ground Beef and Roasted Vegetable Casserole with Mozzarella

Ground beef casserole combines roasted zucchini, bell pepper, onion, and mushrooms with a savory tomato beef mixture. Baked under a layer of mozzarella until melted and bubbling, it makes a hearty one-dish dinner.
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Prep Time 15 minutes
Cook Time 45 minutes
resting 10 minutes
Total Time 1 hour 10 minutes
Servings: 6 servings
Course: Dinner
Cuisine: American
Calories: 370
Ingredients Equipment Method Notes

Ingredients
  

  • 1 zucchini medium, about 8 ounces, cut into 1/2-inch pieces
  • 1 red bell pepper cut into 1-inch pieces
  • 1 yellow onion small, cut into 1-inch pieces
  • 8 oz cremini mushrooms quartered
  • 2 tbsp olive oil
  • 1 tsp kosher salt divided
  • 0.5 tsp black pepper divided
For the beef mixture
  • 1.5 lb ground beef 85% lean
  • 2 cloves garlic minced
  • 1 can (15 oz) tomato sauce
  • 1 tsp Italian seasoning
For the topping
  • 2 cup mozzarella 8 ounces, shredded, low-moisture
  • 1 cooking spray

Equipment

  • 1 18x13-inch rimmed baking sheet
  • 1 12-inch skillet
  • 1 9x13-inch baking dish

Method
 

Roast the vegetables
  1. Heat the oven to 425°F.
  2. Line an 18x13-inch rimmed baking sheet with parchment paper.
  3. Toss the zucchini, bell pepper, onion, and mushrooms with the olive oil, 1/2 teaspoon of the salt, and 1/4 teaspoon of the pepper.
  4. Spread the vegetables in an even layer on the baking sheet.
  5. Roast for 20 to 25 minutes, until the vegetables are tender and browned in spots.
Cook the beef
  1. While the vegetables roast, cook the ground beef in a 12-inch skillet over medium-high heat for 8 to 10 minutes, breaking it into small pieces, until no pink remains and it reaches 160°F.
  2. Stir in the garlic and cook for 30 seconds.
  3. Add the tomato sauce, Italian seasoning, and remaining salt and pepper.
  4. Simmer for 5 to 7 minutes, stirring occasionally.
Assemble and bake
  1. Stir the roasted vegetables into the beef mixture.
  2. Transfer the mixture to a 9x13-inch baking dish lightly coated with cooking spray.
  3. Spread the mozzarella evenly over the top.
  4. Bake at 425°F for 15 to 20 minutes, until the cheese is melted and bubbling around the edges.
  5. Let the casserole rest for 10 minutes before serving.

Notes

For the best browning, spread the vegetables in an even layer on the baking sheet. Refrigerate leftovers for 3 to 4 days; this casserole can be frozen. For a dairy-free option, use dairy-free mozzarella.