Pumpkin Doughnut Muffins

Name: Pumpkin Doughnut Muffins
Ingredients: 10 tablespoons (1 ¼ sticks) unsalted butter, room temperature, plus more for pan; 3 cups all-purpose flour (spooned and leveled), plus more for pan; 2 ½ teaspoons baking powder; ¼ teaspoon baking soda; 1 teaspoon coarse salt; ½ teaspoon ground nutmeg; ¼ teaspoon ground allspice; ⅓ cup buttermilk; 1 ¼ cups pure pumpkin puree (from a 15-ounce can); ¾ cup light brown sugar; 2 large eggs; ¾ cup granulated sugar; 2 ½ teaspoons ground cinnamon; ¼ cup (½ stick) unsalted butter, melted