In a large saute pan, heat oil on high. Add sausage and cook until browned, about 3-5 minutes. Transfer to a side bowl and set aside.
Reduce the heat to medium low and add your onion, garlic, and pepper flakes. Cook until onions are softened, about 8 minutes. Add your oregano, tomatoes and their juices (crushing the whole tomatoes with your hands or a mixer if you prefer), the basil sprig, and the cooked sausage. Add salt and pepper and simmer for about 5 minutes.
Break half of the lasagna noodles in half and place into the meat mixture under the sausage. Distribute them evenly throughout. Take the other half of the noodles and use a spoon to submerge them down into the pan.
Dollop Ricotta over lasagna and mix in with the sauce. Top with Mozzarella and bake in the oven on 325 degrees for 15 minutes. Top with basil, then remove from heat and allow to cool before serving.
*Nutritional information is a calculated guesstimate. Please note that this can change with different brands and modifications you may make to the recipe. For the most accurate information, use a nutritional calculator with the exact brands and measurements you're using with each recipe.