01 - Preheat oven to 375°F. Lightly grease a 6-cup muffin tin.
02 - In a small bowl, mix softened butter with minced garlic and chopped parsley until thoroughly combined.
03 - Flatten each bread slice using a rolling pin. Trim crusts if necessary to fit the muffin cups.
04 - Spread a thin layer of garlic butter on one side of each bread slice and press the slices butter-side-up into the muffin tin, forming bread cups.
05 - Sprinkle grated Parmesan cheese into the bottom of each bread cup.
06 - Crack one egg into each bread cup. Season with salt and black pepper. Top with shredded mozzarella or cheddar if using.
07 - Bake for 16 to 18 minutes until egg whites are set and yolks reach desired consistency.
08 - Let the egg cups cool for 2 minutes, then carefully lift them from the tin with a small spatula.
09 - Serve immediately, garnishing with extra fresh parsley if desired.