Preaheat oven to 450 Fahrenheit.
Using a plastic or wodden knive, slice eggplant into 1/4 inch slices (Metal knives can make the eggplant bitter). Place on a cookie sheet that has been sprayed with olive oil. Spray or brush eggplant with olive oil and sprinkle with a pinch of salt. Place into oven and cook for a about 3 to 4 minuts on each side or just until it starts to brown. Remove and let cool.
Meanwhile, saute sliced mushrooms in a little olive oil for about 4 minutes. Set aside.
Cut the sausage down the length and remove the casing. Mix the ground beef, sausage, onion and garlic in the pan and cook on medium heat, stirring almost constantly to break up and mix the meat. Cook until the meat is browned. Add the oregano, basil, tomatoes and tomato paste, stirring until well mixed. Cook for about 3/4 hour and then add mushrooms. Cook for a further 1/2 hour. (this can make a very hearty and fabulous thick pasta sauce too!).
Cook lasagne noodles according to the package, dran and rinse well with cool water. Set aside.
Combine ricotta cheese, eggs, parmesan cheese and 1/2 of the mozzarella cheese. Add pepper if desired and mix well.
In a lasagne pan, create the following thin layers starting with meat sauce, noodles, cheese mixture; meat sauce, eggplant, meat sauce, noodles, meat sauce remaining cheese mixture then sprinkle with mozzarella cheese.
Bake at 375 degrees for 40 minutes or until the cheese is melted and just starting to brown. Let stand on counter for 10 to 15 minutes before serving.
To reduce the carbs, you can substitute the final layer of noodles with either lightly roasted zucchini or another layer of eggplant.