Heat a large dutch oven (I used a 7 qt one, but a 5 qt size should work too) over medium-high heat on the stovetop. Add olive oil and heat until shimmery.
Add ground beef and ground chicken and season with 1/2 tsp salt and 1/4 tsp pepper. Brown the meat, breaking it apart with a wooden spoon as it cooks. Once the meat is mostly cooked through but still has spots of pink, add onion and garlic and mix to combine. Continue cooking until the meat is cooked through and onion and garlic are fragrant.
Add crushed tomatoes, diced tomatoes, tomato paste, grated carrots, chopped bell pepper, Flavor God seasoning, red pepper flakes, and remaining salt and pepper. Stir to combine all ingredients, then lower heat to a simmer and cover the pot.
Simmer the sauce, stirring occasionally, for 45 minutes. Taste and add more salt as needed as the sauce cooks. In the last 15 minutes of cooking, add the fresh chopped basil. Once the 45 minutes are up, remove the sauce from heat and stir in the baby spinach. Set aside.
In a separate pot, bring about 4 quarts of water to a boil with 1 tbsp of kosher salt. Add pasta, stir, and set timer for 4 minutes (the water will come back up to a boil during this time, but you only need to leave it in the water for 4 minutes total). After 4 minutes, drain the pasta, reserving 1/2 cup of the pasta water, and immediately add the pasta and reserved pasta water into the meat sauce and stir.
Note: The final steps depend on whether you'll be freezing the dish or eating it now. Follow either the "Freezer Prep Instructions" or "Eat It Now Instructions" as applicable.
Pre-heat oven to 350°. Ensure the top rack is placed with enough clearance for your baking dish to fit on the top rack.
If you've cooked the meat sauce in an oven safe dish such as a Dutch oven, you can leave the pasta in the same dish or move it to a greased 9x13" casserole dish. (Note: I prepared half of my pasta to eat now and half for the freezer, so I used an 8x8" casserole dish for baking.)
Mix the parmigiano reggiano and mozzarella cheeses and spread evenly on top of the pasta. Bake uncovered for 30 minutes. Keep an eye on it during the last 10 minutes of baking - if the cheese begins to brown too much, remove it from the oven for serving. Garnish with fresh chopped basil before serving, if desired.
Bake now, then freeze option (great for grabbing individual portions for easy microwave reheating): Pre-heat oven to 350°. Ensure the top rack is placed with enough clearance for your baking dish or Souper Cubes to fit on the top rack.
Bake uncovered for 30 minutes. Keep an eye on it during the last 10 minutes of baking - if the cheese begins to brown too much, remove it from the oven for serving.
Freeze now, bake later option (great for freezing the entire pasta bake, or if you know you'll have time to bake individual portions before serving): For best results, thaw in the refrigerator overnight before baking. Bake uncovered at 350° for 30-40 minutes. Keep an eye on it during the last 10-15 minutes of baking - if the cheese begins to brown too much, cover with foil for remainder of baking time.
To bake individual portions straight from freezer: Place in an oven safe dish and cover with foil. Bake at 350° for 30 minutes, then remove foil and bake another 10-15 minutes.
To bake entire dish straight from freezer: Ensure the dish is safe to go straight from freezer to oven like this one. Bake at 350° for 1 hour, then remove foil and bake another 10-15 minutes until the center is bubbly.
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