Step 1

Preheat oven to Place broccoli on a large baking sheet and lightly drizzle with olive oil. Roast for 7-10 minutes, or until broccoli is starting to get a little brown in small spots. You don't want it fully cooked, but you want some roasty flavor.

Step 2

Melt butter in a medium saute pan. Add onion, and saute over medium low heat for 4-5 minutes. Whisk in flour, and reduce heat to low. Continue cooking for 5 minutes, stirring frequently.

Step 3

Add milk, dry mustard, garlic powder, and salt. Whisk to combine, and cook over medium-low heat until the mixture is slightly thickened. Remove from heat and stir in 1 cup of cheese.

Step 4

Place broccoli in a large baking pan. Pour cheese sauce over the top. Top with the rest of the cheese.

Step 5

Combine butter and melted butter. Sprinkle over the cheese, and bake at 325 for 30 minutes, or until the cheese is melted and bubbly and the broccoli is tender.