Preheat the oven to 400 degrees. Spray a dark roasting pan (preferred) or a stainless steel roasting pan.
Prepare the sauce by stirring the garlic powder, salt, red pepper flakes and bay leaf right into the opened can of crushed tomatoes. Let it sit to absorb the flavors.
Prepare the peppers by rinsing and patting them dry with a paper towel. Cut a circle around the stems to remove them. Cut each pepper in half and remove the seeds and membranes. Cut the halves in half again. Then slice each one into strips about ½ inch wide.
Prepare the onion by cutting off the ends, peeling off the skin, and cutting the onion in half. Then cut each half into vertical slices.
Cut the sausage links in half the short way and place them in a single layer in the greased pan. Add the peppers, then onions.
Drizzle olive oil on each row of sausage. Lightly sprinkle salt on each row. Then sprinkle on pepper and garlic powder, again being sure to season every row.
Bake, uncovered for 30 minutes initially.
Remove the pan of sausage and peppers from the oven and stir the food around, making sure to turn the sausage over. Pour the crushed tomato mixture (or prepared marinara sauce) on top. Return the pan to the oven and bake for another 30 minutes, uncovered.
Split open the hoagies without cutting them all the way through. Broil them face-up on an ungreased sheet pan for 1-2 minutes or until lightly toasted. (If you don't toast them, the sandwich will be soggy.)
To serve, use a slotted spoon or tongs to place two of the sausage halves in a straight line inside each toasted bun. Top with some roasted peppers and onions and add a little extra sauce, if desired. Sprinkle on some basil ribbons and add grated Parmesan, if desired.
Store leftover sausage, peppers and sauce in a sealed container in the refrigerator for up to four days.
Notes
Sauce: If you have marinara sauce made, you can use that without adding anything to it, but the sauce will turn out a bit greasy with the sausage baked in it.Sausage:
Slicing the Italian sausage links in half the short way allows the sauce to take on some sausage flavor while keeping the sandwich manageable to eat.
If you leave the links whole, the sauce will be bland.
Don't slice the sausage into rounds before baking it unless you intend to serve it over pasta instead of in a sandwich. (It's too messy to eat in a sandwich.)
Type of pan to use:
A dark roasting pan works best for this recipe. It enables the Italian sausage to get brown and the tomato sauce to develop a savory, sausage flavor when the crushed tomatoes are added right to the baking pan after the first 30 minutes.
The dark pan cooks down the sauce, reducing it to a thicker texture.
You also can use a stainless steel roasting pan.
An aluminum sheet pan can react with the acid in the tomatoes, so it's not recommended.