12 slices bacon
8 slices pumpernickel bread
whole grain mustard, to taste
apricot preserves, to taste
6 oz Fontina cheese, coarsely grated
6 oz Asiago cheese,coarsely grated
about 1/4 head radicchio, sliced into ribbons
about 1/2 stick butter, room temperature
Cook the bacon: Preheat the oven to 350°F. Position a cooling rack over a baking sheet, then arrange the bacon in a single layer over the rack. Bake until just crispy (but not too crispy), about 25-30 minutes. Remove from the oven, and lifting the bacon with tongs, arrange it on a bed of paper towels, to soak up some of the grease.
Prepare the sandwiches: Spread mustard then apricot preserves on one side of each of the 8 slices of bread, using as little or as much as you like. Arrange the grated cheeses evenly over four of the slices of bread, then top with 3 slices of bacon per sandwich. Arrange the radicchio over the bacon, then top each sandwich with a second slice of bread, mustard and preserve side down. Generously butter the tops of the sandwiches. Then flip the sandwiches over and arrange on a foil-lined baking sheet. Now generously butter the tops of the other slices of bread.
Pre-heat the oven broiler and arrange a rack about 10 to 12 inches beneath the broiler. Toast the sandwiches beneath the broiler until the top slices are toasty and crisp, then flip them over and toast the other sides. By the time the tops and bottoms are toasted, the cheese should be melted. If not, heat the oven to 350°F and bake for a few minutes.