Macaroni with Farmhouse Cheddar and Bacon

INGREDIENTS

• 4 Tbs. unsalted butter, plus more for greasing
• 4 slices baguette or other firm bread, crusts removed, bread torn into crumbs
• 4 thick-cut bacon slices, cut crosswise into 1/2-inch-wide pieces
• 1/4 cup all-purpose flour
• 1/2 tsp. salt, plus more, to taste
• 1/4 tsp. freshly ground black pepper
• 1/4 tsp cayenne pepper
• 3 cups milk, warmed
• 1/2 lb. farmstead cheddar cheese, shredded
• 1/4 lb. white cheddar cheese, coarsely grated
• 1/2 lb. elbow macaroni