Preheat your oven to 375F.
Slice the French bread in half lengthwise and spread some margarine on both halves of the bread.
Place each half of the loaf onto a baking sheet and place them in the preheated oven for 5 minutes or until lightly browned.
While the French bread is baking, cook the sausage in a pan over medium heat until it’s cooked through and no longer pink.
Once the sausage is cooked through, remove it from the pan and drain off any excess fat.
Add the Parmesan cheese, mozzarella slices, Italian seasoning, dehydrated onion, red pepper flakes, garlic powder, tomato sauce, and tomato paste to the pan and stir until all of the ingredients are combined.
Spread the sausage mixture evenly over both halves of the French bread.
Place the baking sheets with the French bread back into the preheated oven for 15 minutes or until golden brown and bubbling on top.
Remove from oven and let cool for 5 minutes before serving.