Crispy panko breadcrumbs add crunch to this rich and cheesy pasta casserole. Slideshow: More Macaroni and Cheese Recipes
Preheat the oven to 425°. Brush a 9-by-13-inch baking dish with butter.
In a medium bowl, whisk the half-and-half with the flour, salt, pepper, and 1 cup of water. Stir in the noodles, both cheeses, and the peppers. Scrape the noodle mixture into the prepared baking dish, and bake until bubbling and the noodles are tender, about 30 minutes.
Preheat the broiler and position a rack 8 inches from the heat. In a small bowl, toss the panko with the 3 tablespoons of melted butter until evenly moistened. Sprinkle the panko mixture over the macaroni and cheese, and broil until browned, 1 to 2 minutes. Garnish with peppers and serve.