Preheat your oven's broiler. 2. Place 6 slices of bread onto a baking sheet. Spread a small handful of the mozzarella cheese over each slice. Top with the remaining 6 slices of bread. Mix together the butter & garlic powder, brush some over the tips of the sandwiches, or spread with the back of a tablespoon. Sprinkle with dried oregano. 3. Place baking sheet under the broiler for 2 to 3 minutes, until golden brown. Remove pan from oven, flip sandwiches, & brush the other sides with butter, & sprinkle with oregano. Return to the broiler, & cook until golden, about 2 minutes. 4. Cut sandwiches in half diagnally, & serve immediately with sauce on the side for dipping.