1. Start by heating the olive oil in a large soup pot over medium heat. This is the base for your sauce. As the oil shimmers, add the onion and season with salt and pepper. Cook for about 5 minutes until the onion becomes fragrant and begins to caramelize, turning a lovely golden color.
2. Next, introduce the bell pepper and garlic to the pot. Stir in the spicy Italian sausage and lean ground beef. As the meat cooks, break it up into smaller pieces, ensuring it browns evenly. This should take about 10 minutes. Your kitchen will start to smell incredible!
3. Once the meat is browned, pour in the chopped tomatoes, tomato paste, dried oregano, and the bay leaf. Add whole milk and 1 cup of water, seasoning again with salt and pepper. Stir everything together and allow it to cook over medium heat for 30 minutes. This simmering time helps deepen the flavor as the sauce thickens slightly.
4. After 30 minutes, if you want even more flavor, you can cook the sauce covered on low heat for up to 3 hours, stirring occasionally. Remember to remove the bay leaf before using the sauce.
5. While your sauce simmers, take a medium bowl and combine the ricotta cheese and basil pesto. This will be a creamy layer in your lasagna.
6. Preheat your oven to 375 degrees F. Get a 9x13 inch pan and grease it to prevent sticking. Start by spreading 1/4 of the Bolognese sauce on the bottom of the dish.
7. Layer in 3-4 lasagna noodles over the sauce. Next, spread half of the ricotta mixture over the noodles. Follow this with another 1/4 of the Bolognese sauce and half of the provolone cheese.
8. Repeat the layering process with another 3-4 lasagna noodles, the remaining ricotta mixture, another 1/4 of the Bolognese sauce, and the remaining provolone cheese.
9. Finish by adding the last layer of lasagna noodles and pouring the remaining Bolognese sauce over the top. Sprinkle with fresh mozzarella and some grated parmesan.
10. Bake uncovered for 45 minutes or until the top is golden and bubbly. Patience is key! Once done, let it stand for 10 minutes before serving to allow it to set, making it easier to slice.
