Loaded Tater Tot Casserole

Name: Loaded Tater Tot Casserole
Ingredients: 4 slices thick-cut bacon; 1 cup chopped yellow onion (1 medium); 2 tablespoons all-purpose flour; 1/8 teaspoon cayenne pepper (optional); 2 cups plus 1 tablespoon milk, divided; 2 cups shredded sharp cheddar cheese (8 ounces), divided; 1 (32-ounce) package frozen bite-sized potato nuggets (Tater Tots®), thawed; 3/4 cup sour cream, divided; 1 bunch green onions, white and pale green parts chopped (2/3 cup), divided; 1 tablespoon chopped fresh dill