01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a large mixing bowl, whisk together flour, crushed cornflakes, granulated sugar, baking powder, baking soda, salt, cinnamon, and nutmeg until evenly blended.
03 - In a separate bowl, whisk together pumpkin puree, eggs, melted butter, whole milk, and vanilla extract until the mixture is smooth.
04 - Add wet ingredients to the dry mixture and gently stir just until combined, being careful not to overmix.
05 - Divide the batter evenly into the prepared muffin tin.
06 - In a small bowl, combine cornflakes, melted butter, and brown sugar. Sprinkle the topping evenly over each portion of batter.
07 - Bake for 20 to 22 minutes, or until a toothpick inserted in the center comes out clean.
08 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.