Step 1

Preheat the oven to 350 degrees F.

Step 2

Grease a 2-quart casserole dish.

Step 3

In a saucepan, cook the onion in the butter over medium-low heat until softened and translucent, about 5 minutes.

Step 4

Stir in the flour, the garlic powder, and the pepper and cook for 2 minutes.

Step 5

While whisking, gradually pour in the milk.

Step 6

Increase the heat to medium and whisk until the mixture is thick and bubbly.

Step 7

Transfer the saucepan from the heat and add the dry mustard, the paprika, the cream cheese, and 1 1/2 cups of the cheddar cheese, stirring until the cheese is melted.

Step 8

Taste the sauce for seasoning and add salt to taste.

Step 9

In a pot of boiling water, add the broccoli and cook until still slightly crisp, about 2 minutes.

Step 10

Drain the broccoli.

Step 11

Stir the broccoli, the cheese sauce, and the rice together.

Step 12

Pour the mixture into the prepared casserole dish.

Step 13

Top the casserole with the remaining cheese and bake until bubbly and the cheese is lightly browned, about 35 minutes.

Step 14

Serve hot.