There's no need to limit yourself to just one of these little muffins with butter tops coated in a cinnamon-sugar mixture.
Preheat oven to 375 degrees. Butter a mini-muffin tin, and set aside. In a small bowl, combine 1/2 cup sugar and 1 tablespoon cinnamon; set aside.
In a large bowl, combine flour, baking powder, salt, and remaining teaspoon cinnamon; whisk to combine. In a small bowl, combine 6 tablespoons butter, remaining 1/2 cup sugar, buttermilk, and egg; whisk to combine. Using a large rubber spatula, fold butter mixture into flour mixture; use no more than 10 strokes. The mixture should be lumpy.
Spoon 1 tablespoon batter into each prepared cup, and bake until tops are nicely golden, about 8 minutes. Remove from oven; let cool in pan 10 minutes before transferring to a wire rack.
Dip top of each muffin in remaining 4 tablespoons melted butter, and roll in reserved cinnamon mixture. Serve warm or at room temperature.
You'll need a two-tablespoon-capacity mini-muffin tin for this recipe.