The whole family loved it! I'm doubling up on the ingredients for the next batch

1. Heat up your oven to 375°F (190°C).
2. Initiate by removing the skin from the sweet onions and cutting them into thin slices.
3. Put the thinly sliced onions into a 9x13 inch baking dish that has been coated with grease.
4. Distribute the sliced butter evenly over the bottom of the baking dish.
5. Insert the baking dish into the preheated oven for 5-7 minutes, or until the butter has melted and become bubbly.
6. Take a separate bowl and vigorously whisk together the all-purpose flour and milk until they are thoroughly blended.
7. Integrate the garlic powder, onion powder, paprika, salt, and black pepper into the mixture and whisk once more to combine them.
8. Pour the milk and flour amalgamation over the sliced onions in the baking dish, ensuring an even coating over the onions.
9. Sprinkle the shredded cheddar cheese on the surface of the onion mixture.
10. Bake the casserole in the preheated oven for approximately 25-30 minutes, or until the cheese has melted and turned bubbly.
11. Allow the casserole to cool for a brief period before serving.