Preheat oven to 350°F (175°C) and line a 12-cup muffin tin with liners or grease lightly.
- In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, nutmeg, ginger, and cloves.
- In a separate bowl, mix pumpkin purée, brown sugar, granulated sugar, eggs, oil or butter, vanilla, and milk until smooth.
- Add the dry ingredients to the wet ingredients and stir until just combined—do not overmix.
- In a small bowl, combine the cinnamon swirl ingredients: brown sugar, cinnamon, and melted butter.
- Fill muffin cups halfway with batter, add a spoonful of cinnamon swirl, then top with more batter. Use a toothpick to gently swirl the layers.
- Bake for 18–22 minutes or until a toothpick inserted into the center comes out clean.
- Cool in the pan for 5 minutes, then transfer muffins to a wire rack.
- Mix glaze ingredients until smooth and drizzle over cooled muffins.