3/4c panko bread crumbs
1 oz Parmesan cheese, grated (1/2 cup)
3T unsalted butter, melted plus 3T unsalted butter
Salt and pepper
2 lbs broccoli florets, cut into 1 inch pieces
1 shallot, minced
2 cloves garlic, minced
3T all purpose flour
3c half and half
6 oz extra sharp cheddar cheese, shredded (1 1/2 cups)
2 oz American cheese, chopped (1/2 cup)
2 tsp hot sauce
1 tsp dry mustard
1. Adjust oven rack to upper middle position and heat oven to 400º. Combine panko, Parmesan, melted butter, and 1/4 tsp salt in a bowl; set aside.
2. Toss broccoli with 1/2 tsp salt in a large bowl. Cover and microwave until broccoli is bright green and just tender, 8 to 10 minutes. Drain broccoli in colander, then transfer to 9x13 baking dish.
3. Melt remaining 3T butter in medium saucepan over medium heat. Add shallot and garlic and cook until softened, about 2 minutes. Whisk in flour and cook for 1 minute. Slowly whisk in half and half. Increase heat to medium-high and bring mixture to a boil. Off heat, quickly whisk in cheddar, American cheese, hot sauce, mustard, 1 1/2 tsp salt, and 1/4 tsp pepper until smooth.
4. Pour cheese sauce over broccoli in dish and stir to combine, Sprinkle reserved panko mixture over top. Bake, uncovered, until casserole is bubbling around edges and golden brown on top, about 15 minutes. Let cools for 15 minutes. Serve.
To make ahead: Panko mixture and microwaved, drained brocoli can be refrigerated separately for up to 24 hours. To serve, continue from step 3, increasing baking time by 5 minutes.