Pre-heat broiler. Slice as many pieces off of the loaf as needed. Use the sourdough rounds bought in the bakery, I use the unsliced one, so I can get the slices as thick as I like.
Drizzle each piece with a good amount of olive oil on one side only. Sprinkle generously with garlic powder and parmesan cheese, place under the broiler, on the rack with foil, until lightly browned. Switch oven to 450 and bake about 5 minutes, or until desired crispiness is reached.
NOTE: My husband like this better when I use butter, in place of the olive oil-both ways are great.