Preheat the oven to 375°F and spray a standard muffin pan with gluten-free nonstick cooking spray.

Add the Bisquick, sugar (if using), and salt to a large bowl. Whisk together until combined. Use a fork (a pastry cutter or your fingers work great too!) to cut the shortening into the dry ingredients. Work the shortening in until it resembles coarse sand.

Add the beer and mix to combine. Stir in the milk, as needed, to get a wet enough consistency that the dough will hold together (similar to biscuits).

Divide the dough into 12 equal portions in the muffin pan and smooth out the tops.

Bake for 10 minutes, then remove from the oven and brush with the melted butter. Continue to bake for an additional 10 minutes or until baked all the way through.

When the muffins are done, tilt them in the pan to let some of the steam release and prevent condensation from forming on the bottom. Cool the muffins for 5 minutes, then serve.