Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, add the lasagna noodles a few at a time, and return to a boil. Cook the pasta uncovered, stirring occasionally, until the pasta has cooked through, but is still firm to the bite, about 10 minutes. Remove the noodles to a plate.

Cook sausage, ground beef, and garlic in a large skillet over medium-high heat, stirring occasionally, until browned and crumbly, 5 to 7 minutes. Drain any excess grease.

Stir in diced tomatoes, tomato sauce, parsley, basil, oregano, and sugar. Bring to a boil over high heat, then reduce the heat to medium-low and simmer, stirring occasionally, until thickened, about 30 minutes.

In a bowl, stir sour cream, 1/2 of the mozzarella, Parmesan, eggs, salt, and pepper together in a bowl

Assemble the lasagna: Spread a thin layer of meat sauce evenly over the bottom of a 9x13-inch baking dish. Cover with 1/3 of the lasagna noodles, 1/3 of the remaining meat sauce, and 1/3 of the cheese mixture; repeat layers two more times with remaining noodles, sauce, and cheese mixture. Sprinkle remaining mozzarella evenly over top.

Bake in the preheated oven until sauce is bubbly and the cheese is golden brown, about 30 minutes