Gluten Free Lemon Blueberry Muffins

Bob's Red Mill gluten free baking flour

baking powder (for gluten allergies, check that it's a gluten-free formula)

salt

butter

sugar, plus a tablespoon or so to sprinkle on top

finely grated lemon zest (one lemon is plenty for this much)

egg

buttermilk (tip: since you are already zesting your lemon, you can use fresh lemon juice and whole milk or heavy cream - I'll note that below)

blueberries