Special equipment: a standard 12-cup muffin tin
Preheat the oven to 400 degrees F. Arrange the bacon, closely spaced, on a rimmed baking sheet. Bake, flipping halfway through, until the fat is rendered and the bacon is lightly browned but not at all crisp, about 10 minutes. Drain on paper towels.
Meanwhile, add the sausage to a medium nonstick skillet over medium heat. Cook, crumbling with a wooden spoon, until no longer pink, about 4 minutes. Drain alongside the bacon.
Reduce the oven temperature to 375 degrees F. Beat the eggs and half-and-half in a large bowl. Season with 1/2 teaspoon salt and a generous grinding of black pepper. Fold in the bread cubes and the cooked sausage and let soak for 5 minutes.
In a 12-cup muffin tin, line each cup with a slice of the bacon, making a ring so the ends overlap. Divide the bread mixture among the cups, using a tablespoon to keep it neat. Sprinkle the tops with half of the Cheddar, followed by the red pepper and scallion and then the rest of the Cheddar.
Bake until puffed and golden and a tester inserted into the center comes out mostly clean, about 20 minutes. Remove the bread puddings from the muffin tin with a fork. Serve hot or warm.