Preheat oven to 450 degrees. 

Heat oil in skillet over medium heat.  Add onions, salt, and sugar, and cook until onions are soft and golden, stirring occasionally, for about 25 minutes.  Remove from heat and stir in basil, garlic powder, and seasoned salt to taste.

Place bread shell(s) on cookie sheet, heap onion mixture on top, and top with cheese.

Bake 10-12 minutes, until cheese is melted and golden.