Fill a large pot of water with salt and bring to a boil. Once boiling, cook the lasagna noodles according to the directions until al dente. Drain and set aside.
For the meat sauce: In a large skillet over medium heat, add in the olive oil. Once hot, add in the onion and garlic. Stir and cook until onions are transparent, about 5 minutes.
Add in the ground meat and ground sausage. Cook until no longer pink, about 5-10 minutes. Season with salt and pepper.
Add in the dried basil, jar of marinara sauce, and broth. Stir together and reduce heat to medium-low. Cover and cook for 30-45 minutes or until thickened, stirring occasionally.
While the meat is cooking, make the béchamel sauce: In a large pot, melt the butter over medium-low heat.
Once melted, whisk in the flour until there are no lumps.
Continue to stir and slowly add in the heavy cream, nutmeg, and ½ cup of the parmesan cheese. Constantly stir for 3-5 minutes. The mixture should become smooth, thick and creamy. Remove from heat and set aside.
Preheat oven to 350℉.
To assemble: In large deep baking dish, spread a small amount of béchamel sauce into a thin, even layer. Then place a layer of lasagna noodles, ricotta, more béchamel sauce, meat sauce, and mozzarella cheese. Repeat until all ingredients are used.
Top with the mozzarella and remaining ½ cup of parmesan cheese.
Bake for 20-25 minutes or until the cheese bubbles. Let cool for 15 minutes.
Cut into individual servings. Serve.