Set your oven to broil. Line baking sheet with aluminum foil and lay 6 slices of bread over top.
In a small bowl, stir together butter, garlic, garlic powder, and dried parsley flakes until well combined. Spread about half a tablespoon evenly over each slice of bread.
Broil until golden brown and lightly crisp. Flip over and spread another half tablespoon over each slice of bread.
Top with 1/4 cup grated cheese per slice and broil until cheese is bubbly and melty and the edges are golden and crisp. Cool 2 minutes, then slice and serve.