This easy, one-pan casserole has all of the classic Italian flavors, plenty of melted cheese, and a couple of easy nutrition upgrades. Quinoa makes it extra filling, while brown lentils practically disappear into the ground beef or turkey and add a little extra protein and fiber. {Gluten-Free}
There is just something about the convenience of a well-balanced casserole where six generous servings cook in one pan.
This one combines ground beef or turkey with quinoa, veggies, marinara, mozzarella and parmesan cheese. I also add a can of brown lentils to stretch the protein a little further and add some extra fiber – and honestly, you really don’t notice them once everything is mixed together.
You can absolutely leave them out if you prefer.
It’s hearty, cheesy, and really easy to throw together, which makes it a great weeknight dinner when you want something cozy but still balanced. I hope you love this one as much as my Mexican Quinoa Casserole!
Why I Love This Recipe
If you absolutely love this recipe, make sure to try my other casseroles!
Ingredients
This casserole makes about 6 large servings!
- 1 lb lean ground beef or turkey.
- 8 oz mushrooms, finely chopped.
- 1 small or medium yellow onion, finely diced.
- 2 bell peppers, finely diced.
- 2 medium carrots, finely diced.
- 5 cloves garlic, minced.
- 15 ounces cooked brown or green lentils. I use one low sodium can of lentils.
- 1 cup uncooked quinoa, rinsed.
- 2 cups marinara sauce. I love using Rao’s – either the classic marinara or tomato basil!
- 1 cup low-sodium beef broth.
- 1 tablespoon Italian seasoning.
- 1 teaspoon garlic powder.
- 1/2 teaspoon salt.
- 1/4 teaspoon black pepper.
- 1 1/2 cups shredded mozzarella.
- 1/4 cup grated Parmesan.
- 1 tablespoon of olive oil or avocado spray.
- Balsamic glaze, to finish, optional.
- Fresh basil, to finish, optional.
Step-By-Step Directions
This casserole comes together in just a few simple steps. Start by browning the ground beef or turkey with the vegetables, garlic, and seasonings, then stir in the lentils so they blend right into the mixture.
From there, everything goes into the baking dish with the uncooked quinoa, marinara, and broth before being topped with mozzarella and Parmesan and baked until bubbly and golden. I love finishing it with a little balsamic glaze and fresh basil for extra flavor.
- Preheat oven to 400°F.
- Heat a large skillet over medium-high heat. Spray with avocado oil spray. Add the ground turkey or beef, onion, mushrooms, bell peppers, and carrots. Add in the seasonings. Cook until the meat is browned and the vegetables begin to soften, about 7–8 minutes.
- Add the minced garlic and cook for about 30 seconds, until fragrant. Stir in the drained lentils and use the back of a wooden spoon or spatula to lightly mash some of the lentils into the ground meat. Turn off the heat.
- Add the rinsed uncooked quinoa to the baking dish.
- Spread the beef and vegetable mixture over the quinoa.
- Whisk together the marinara and beef broth.
- Pour evenly over the casserole and gently stir just enough to make sure the quinoa is submerged in liquid.
- Cover tightly with foil and bake for about 40 minutes, or until the quinoa is tender and most of the liquid has been absorbed.
- Remove the foil and sprinkle with the mozzarella and Parmesan.
- Return to the oven uncovered for about 5–10 minutes, until the cheese is melted.
- Broil for 2–4 minutes until the top is bubbly and lightly browned. Let sit for about 5–10 minutes before serving. Finish with optional balsamic glaze, fresh basil, and red pepper flakes!
- Store leftovers in an airtight container in the fridge for up to 4 days or in the freezer for up to 3 months.
Frequently Asked Questions
Can I Prep This Ahead of Time?
I would recommend cooking the brown lentil and beef mixture ahead of time. Then, easily assemble the casserole when you’re ready to bake!
I haven’t tested assembling the entire casserole ahead of time, but it should work well. Assemble, cover tightly, and refrigerate for up to 24 hours before baking. The quinoa may absorb some of the liquid as it sits, so add a small splash of broth if it looks noticeably dry before baking. You may also need a few extra minutes of baking time since the casserole will be starting cold.
Can I Leave Out the Lentils?
Yes. They’re optional, although they add fiber, protein, and help make the casserole more filling.
What If Adding Beans or Lentils Makes Me Gassy?
They can for some people, especially if you don’t eat lentils or other high-fiber foods very often. Rinsing canned lentils well and starting with a smaller portion may help, and most people tolerate them better when fiber intake is increased gradually.
Try starting with half a can instead. Keep in mind that even when using the entire can, it’s divided between six servings, so the amount of lentils per serving is relatively small.
How Do I Know When the Casserole is Done?
The quinoa should be tender and most of the liquid absorbed.
Can I Use Rice Instead of Quinoa?
I have not tested rice with this specific recipe – it usually needs a bit more liquid and a longer cooking time. Add 1/2 cup additional broth and cook for 20 minutes and test to see if the rice is tender before adding the cheese!
Cheesy Italian One Pan Quinoa Casserole
Ingredients
- 1 pound lean ground turkey or ground beef
- 1 cup uncooked quinoa, rinsed or use pre-rinsed
- 8 ounces mushrooms, finely chopped
- 1 small or medium yellow onion, finely diced
- 2 bell peppers, finely diced
- 2 medium carrots, finely diced
- 5 cloves garlic, minced
- 15 ounces canned brown lentils, drained and rinsed
- 2 cups marinara sauce I love Rao's!
- 1 cup low sodium beef broth
- 1½ cups shredded mozzarella cheese
- ¼ cup grated parmesan cheese
- 1 tablespoon Italian seasoning
- 1 teaspoon garlic powder
- ½ teaspoon salt
- ¼ teaspoon pepper
- 1 tablespoon olive oil or avocado spray
- Fresh basil
- Balsamic Glaze
- Red Pepper Flakes
Method
- Preheat oven to 400°F.
- Heat a large skillet over medium-high heat. Spray with avocado oil spray. Add the ground turkey or beef, onion, mushrooms, bell peppers, and carrots. Add in seasonings. Cook until the meat is browned and the vegetables begin to soften, about 7–8 minutes.
- Add the minced garlic and cook for about 30 seconds, until fragrant. Stir in the drained lentils and use the back of a wooden spoon, a potato masher, or spatula to lightly mash some of the lentils into the ground meat. Turn off the heat.
- Add the rinsed uncooked quinoa to the baking dish.
- Spread the beef and vegetable mixture over the quinoa.
- Whisk together the marinara and beef broth. Pour evenly over the casserole and gently stir just enough to make sure the quinoa is submerged in liquid.
- Cover tightly with foil and bake for about 40 minutes, or until the quinoa is tender and most of the liquid has been absorbed.
- Remove the foil and sprinkle with the mozzarella and Parmesan. Return to the oven uncovered for about 5–10 minutes, until the cheese is melted.
- Broil for 2–4 minutes until the top is bubbly and lightly browned. Let sit for about 5–10 minutes before serving. Finish with optional balsamic glaze, fresh basil, and red pepper flakes!
- Store leftovers in an airtight container in the fridge for up to 4 days or in the freezer for up to 3 months.