reheat oven to 350°F and line a 12-cup muffin tin with liners or spray with nonstick spray.
Whisk together pumpkin puree, melted butter, sugar, egg, and vanilla until smooth.
Combine dry ingredients: flour, baking soda, baking powder, salt, and cinnamon.
Fold dry ingredients into wet ingredients until just combined.
Prepare the cinnamon swirl: mix melted butter, brown sugar, and cinnamon in a small bowl.
Fill muffin cups halfway with batter, add cinnamon swirl, then top with more batter. Use a toothpick to lightly swirl the cinnamon mixture through the batter.
Bake for 20-25 minutes or until a toothpick inserted comes out clean and tops are golden brown.
Cool slightly before drizzling with cream cheese glaze or a simple glaze.