Preheat your oven to 425°F (218°C). Line a 12-count muffin tin with paper liners or grease them well with non-stick spray. Using a high initial temperature is the secret to getting those tall muffin tops.
In a medium bowl, whisk together the flour, baking soda, baking powder, salt, pumpkin pie spice, and cinnamon. Ensure there are no large clumps of flour or spices left in the mixture.
In a large bowl, whisk together the granulated sugar, brown sugar, eggs, vegetable oil, pumpkin puree, milk, and vanilla extract until the mixture is smooth and well combined.
Gently fold the dry ingredients into the wet ingredients using a spatula. Mix only until no streaks of flour remain. Be careful not to overmix, as this can make the muffins tough.
Divide the batter evenly among the 12 muffin cups, filling them all the way to the top. Sprinkle with coarse sparkling sugar if desired. Bake at 425°F for 5 minutes, then, without opening the oven door, reduce the temperature to 350°F (177°C) and bake for another 15-18 minutes or until a toothpick comes out clean.
Let the muffins cool in the tin for about 5-10 minutes before transferring them to a wire rack to cool completely. This prevents the bottoms from becoming soggy.