Crunchy Layered Potato Casserole

Ingredients

• 8 slices bacon
• 1 small onion, thinly sliced
• 1 small bell pepper, thinly sliced
• 1 clove garlic, minced
• 2 cups leftover mashed potatoes (with butter, salt, pepper, etc.)
• ½ cup sour cream
• 3 medium potatoes, boiled or baked whole, then sliced ¼-inch thick
• ½ cup panko breadcrumbs
• 2 tablespoons butter, cut into tiny cubes
• 1 cup shredded colby jack, cheddar, or pepper jack cheese
• salt, to taste
• pepper, to taste