In a large skillet or dutch oven, brown ground beef and sausage together, adding in diced onions as the meat browns. Drain and return to skillet.
Turn down heat to low. Add in tomato paste, crushed tomatoes and combine with meat. Add Italian seasoning, garlic, salt and pepper and let simmer for 10-15 minutes, stirring occasionally.
While meat sauce is simmering, bring water to boil in large pot. Add lasagna pasta and cooked just until al dente. Drain and rinse with cold water. In a small bowl, whisk together the ingredients for the ricotta cheese filling and set aside.
To assemble, spoon about 1 C meat sauce in bottom of a deep ungreased 13x9 dish. Layer 3 noodles lengthwise in dish over meat sauce. Layer 2 more noodles lengthwise over the seams between the 3 noodles. Spoon 1/2 of remaining meat sauce over noodles. Cover with 1/2 ricotta cheese mixture. Top with 1/2 of mozarella and Parmesan cheeses. Repeat starting with noodles.
Bake in preheated oven uncovered for 25 minutes. Cover and continue to bake for another 25 minutes or until bubbly around edges. To make slicing easy, let cool 10-15 minutes before serving.
For a spicy kick, add 1 tsp crushed red pepper to meat sauce!