Preheat the oven. Set it to 400°F (200°C).
Lightly grease a 12-cup muffin tin with nonstick spray or a thin swipe of butter.
Par-cook the bacon. This is the key to crisp cups. Lay bacon on a sheet pan and bake for 8–10 minutes until it begins to render fat and turns lightly golden but still flexible. Don’t let it get fully crisp yet.
Line the muffin cups. While the bacon is warm and pliable, wrap one slice around the inside wall of each muffin cup to form a ring.
If the slices are short, overlap ends slightly. For extra crisp bottoms, you can press a small piece of bacon or place a round of parchment at the base.
Add optional fillings. If using veggies, keep them dry and pre-cooked if they release water (like spinach or mushrooms). Add a small pinch to the bottom of each cup.
Avoid overfilling—about a tablespoon per cup is enough.
Crack in the eggs. Crack one egg into each bacon-lined cup. If you prefer a firmer yolk, gently pierce the yolk with a toothpick once; don’t stir.
Season and top with cheese. Sprinkle each egg with a pinch of salt and pepper. Add a small mound of shredded cheese over the whites, leaving the yolk visible if you like it runny.
Bake. Return the tray to the 400°F (200°C) oven and bake 10–14 minutes, depending on desired doneness. For runny yolks, start checking at 10 minutes. For set yolks, plan on 12–14 minutes.
Ovens vary, so watch closely near the end.
Rest briefly. Remove the pan and let cups sit 2–3 minutes. This helps them firm up and release cleanly.
Garnish and serve. Use a small offset spatula or spoon to lift each cup out. Top with chopped chives or parsley.
Serve hot with toast, avocado, or fruit.