Preheat your oven to 425°F (220°C) conventional (see note 1 if using a convection oven) and line a 12-hole muffin tray with muffin liners. Set aside.
Make the topping: In a small bowl, mix together sugar and cinnamon. Set aside.
In a medium bowl, sift together the flour, cornstarch, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and cloves. Whisk to combine and set aside.
In a large bowl, whisk together the sugar, eggs, oil, pumpkin purée, milk, and vanilla until well combined.
Add the dry ingredients to the wet and whisk gently until just combined (do not overmix).
Divide the batter evenly between the muffin liners, then tap the tray lightly on the counter to release air bubbles. Sprinkle the cinnamon sugar topping evenly over the muffins.
Bake at 425°F (220°C) for 8 minutes, then reduce the oven temperature to 350°F (180°C) and bake for a further 12 minutes, or until a toothpick inserted in the centre comes out clean or with a few moist crumbs.
Allow the muffins to cool in the tray for 10 minutes before transferring to a wire rack to cool completely.