Arrange baguette slices in a single layer on a large baking sheet. Bake 8-10 minutes, until lightly toasted. Remove from oven.
In a large skillet, brown the sausage, breaking it up as it cooks. Add the tomato sauce and bring to a simmer. Cook over low heat for 15 minutes.
Mix together ½ cup parmesan cheese and ricotta cheese. Evenly spread cheese mixture on crostini, about ½ tablespoon per slice. Top with sauce mixture and sprinkle with remaining parmesan and mozzarella cheese.
Return to oven and bake for 3-5 minutes, until the cheese starts to melt. Arrange on serving plate, garnishing with basil, if desired. Serve immediately.