16ounces(4 cups) sharp or extra-sharp cheddar cheesefreshly grated
Freshly ground black pepperto taste
Adjust oven rack to center position. Preheat oven to 425°F.
Prepare potatoes by washing, drying, and pricking with a fork. Lightly coat each potato with olive oil (I sprinkle a few drops on top and rub it all over with my hand). If desired, sprinkle oiled potatoes with kosher salt. Place potatoes directly on oven rack, allowing a bit of space between each one. Bake for 45 minutes to an hour or until potatoes are tender all the way to the center when pricked with a fork.
Fill a large pot with lightly salted water and bring to a boil over high heat. Cook frozen broccoli according to package directions. (Alternatively, if using fresh broccoli, steam or boil to desired tenderness...but it should be tender enough to puree into the cheese sauce later, if desired.) Drain broccoli and set aside.
In the same pot that was used to cook the broccoli, prepare cheese sauce. Place over medium heat and melt 4 tablespoons butter. Use a whisk to stir in flour, whisking continuously until light golden brown, about 2 minutes. Continue to whisk while slowly and gradually adding milk. Whisk until sauce is smooth and thickened, between 5 to 10 minutes. Remove pot from heat. Add grated cheese, ½ cup at a time, stirring until completely melted and smooth before adding more. Once all cheese has been incorporated and cheese sauce is smooth, stir in garlic salt, chili powder, and pepper, to taste.
Stir half of the cooked broccoli into the cheese sauce. Use an immersion blender (or potato masher) to purée/mash the broccoli until the sauce is smooth. Stir in the remaining cooked broccoli florets. Taste sauce and adjust seasonings, adding additional salt and pepper, if necessary.
Immediately slice open baked potatoes and serve broccoli cheese sauce on top.
Cheese sauce is easy to make but also easy to mess up if you don't follow the directions exactly. Cheese should be freshly grated (the packaged, pre-grated cheese has an additive that keeps it from sticking together but can also make for lumpy melting). Room temperature milk works best (I just zap it in the microwave to take off the chill). Be sure to take the pot off the heat and add the cheese very gradually, stirring well and allowing it to melt completely between additions.
If you prefer a completely smooth sauce, you may purée all of the broccoli into the cheese sauce. Alternatively, if you wish to leave all of the cooked broccoli florets whole, that's okay, too.
See ideas in the body of this post (above the recipe) for ideas on using up leftover cheese sauce.