1 pound bacon
2 tablespoons softened butter
12 slices sandwich bread
4 ounces grated cheddar cheese
4 ounces grated pepper jack cheese
2 1/2 cups milk
Six eggs
Four avocados, pitted and scored
Two small roma tomatoes, small-diced
One small red onion, small-diced
One jalapeño, seeds and membranes removed, minced
Juice of two limes
One pinch salt
One bunch cilantro, chopped
Preheat the oven to 400F. Cut six of the bacon slices in half, and arrange both the whole- and half-slices on a rack set over a baking sheet. Bake 15 to 20 minutes, until crisp, then set aside.
Reduce the oven temperature to 350F.
Butter a 9-by-13-inch casserole dish and one side of six slices of bread. Place the six unbuttered slices in the dish, and top with the cheddar cheese. Add the halved slices of bacon: two per sandwich. Top with the pepper jack cheese, and finish with the buttered slices of bread, buttered-side up.
Whisk together the milk and eggs, and pour over the casserole. Allow it to sit for 20 minutes.
Bake the casserole for 30 to 40 minutes, until the top is browned and the custard is set.
Meanwhile, prepare the guacamole. Scoop the avocado flesh into a bowl, and mash slightly with a fork. Add the tomatoes, onion, jalapeño, lime juice, and salt. Chop the remaining bacon, and add bacon and cilantro to the guacamole to taste.
Top each grilled cheese sandwich with a heaping spoonful of guacamole, and garnish with cilantro and chopped bacon.