Cook the bacon in a skillet over medium heat until crisp. Drain on paper towels, chop, and set aside.
Using the bacon drippings, sauté the diced onion until softened (about 4–5 minutes). Sprinkle in 1 tablespoon of flour and whisk until combined. Season lightly with salt and pepper. Set aside.
In a large mixing bowl, whisk together the milk and remaining flour until smooth. Add the eggs and whisk again until fully combined.
Stir in the sugar, melted butter, both cans of corn, the cooked onions, chopped bacon, paprika, and additional salt and pepper to taste.
Pour the mixture into a greased 8x8 baking dish. Bake uncovered at 350°F for 50–60 minutes, until the center is set and the top is golden brown.
Let the casserole rest for 15 minutes before slicing—it helps the pieces hold together beautifully.
Recipe can be doubled and baked in a 9x13 dish, perfect for holidays or feeding a crowd.