3 tablespoons unsalted butter, melted
8 slices white or whole-wheat sandwich bread
6 slices bacon
6 large eggs
Coarse salt and ground pepper
Preheat oven to 375 degrees. Lightly butter 6 standard muffin cups. With a rolling pin, flatten bread slices slightly and, with a 4 1/4-inch cookie cutter, cut into 8 rounds. Cut each round in half, then press 2 halves into each muffin cup, overlapping slightly and making sure bread comes up to edge of cup. Use extra bread to patch any gaps. Brush bread with remaining butter.
In a large skillet, cook bacon over medium, until almost crisp, 4 minutes, flipping once. (It will continue to cook in the oven.) Lay 1 bacon slice in each bread cup and crack an egg over each. Season with salt and pepper. Bake until egg whites are just set, 20 to 25 minutes. Run a small knife around cups to loosen toasts. Serve immediately.
Standard muffin pans come in 6- or 12-cup size; if baking 6 items in a 12-cup pan, leave empty space in between. Nonstick pans are nice but not essential. Beware of very thin pans, which often lead to burning. Place pans on a baking sheet to make them easier to get in and out of the oven.