This recipe is for six people, but it's really easy to make a few or feed a crowd, budgeting two eggs per person and using two pieces of bacon for each egg. If you make them in a muffin tin and you don't fill all the wells, be sure to add a little water to each of the empty wells before baking to keep the pan from scorching. —vvvanessa
Cut the bacon in half so that you have 48 short slices instead of 24 long ones. Cook the bacon in one-layer batches until it's about halfway done, rendering off a good amount of the fat. The goal is to keep the bacon moist and pliable, not crispy. It should take about 2 minutes on each side. Transfer bacon to a newspaper-lined platter until all of it is cooked.
Preheat oven to 400ºF.
Set 12 small custard ramekins, each about 3 inches in diameter, on a baking sheet, or use a standard muffin tin. Set a slice of tomato in each well-- it should fit in the bottom, so cut to fit as necessary.
Use 4 half-slices of bacon to line the sides of each compartment. Break one egg into the center of each well. Top each egg with a sprinkle of salt and pepper.
Bake eggs in the oven for 10-15 minutes. For looser yolks, cook until just as the whites turn opaque; for firmer eggs, the whites should be almost set. Keep in mind that the eggs will continue to cook a bit after they're pulled from the oven.
Remove the eggs from oven. Serve in the ramekins or, with a fork or tongs, carefully remove each bacon and egg cup from its receptacle, draining off excess oil as necessary. Garnish with finely minced chives if desired. Serve with hot, buttered toast or pop in the middle of a toasted English muffin.