In a large skillet, heat the olive oil over medium-high heat. Add the ground beef and Italian sausage, breaking apart with a wooden spoon. Cook until browned and cooked through, about 8 to 10 minutes. Drain excess grease and set aside. If you prefer a finer texture, pulse the meat in a food processor for a few seconds.
In the same skillet, add a bit more olive oil if needed. Add the garlic, stirring constantly for 30 seconds until fragrant. Next, add the onion, bell pepper, and spinach. Cook for 2 to 3 minutes until softened, then remove from heat. Pulse this mixture in the food processor until nearly pureed, then return it to the skillet.
Add the whole peeled tomatoes to the skillet, squishing them into the mixture. Stir in the tomato sauce and Italian seasoning, along with salt and pepper to taste. Reduce the heat and let it simmer for 20 to 30 minutes, stirring occasionally. Right before you're ready to assemble the lasagna, mix in the reserved meat and fresh basil.
While the sauce simmers, bring a large pot of salted water to a boil. Add the lasagna noodles and cook them for half the time indicated on the package. Drain in a colander and drizzle a little olive oil to prevent sticking. If you’re using no-boil noodles, you can skip this step.
In a medium saucepan over medium heat, melt the butter. Once melted, whisk in the flour to create a roux, cooking for about 2 minutes. Gradually whisk in the milk, continuing to stir until it thickens, about 5 to 7 minutes. Season with salt and pepper.
Set your oven to 350 degrees Fahrenheit. Lightly grease a 9X13-inch baking pan with cooking spray. Remember, you’ll want to divide your sauces into thirds for layering, so keep that in mind as you assemble.
Start with 3 lasagna noodles on the bottom of the greased pan. Spread a layer of red sauce, then drizzle with béchamel, and sprinkle with Parmesan and mozzarella. Repeat the layers until you’ve used all ingredients, finishing with a layer of sauce and cheese on top.
Place the assembled lasagna in the oven and bake for 40 to 50 minutes, or until it’s hot and bubbly. Once done, let it rest for at least 20 minutes before slicing to help it set.
Pair your Homemade Lasagna with garlic bread or homemade breadsticks along with a fresh green salad for a complete meal.
