In a small dish combine granulated sugar and cinnamon; set aside until needed.
Adjust an oven rack to the middle position; preheat oven to 375 degrees (F). Line a 12-cup muffin tin with paper liners; spray lightly with non-stick spray; set aside.
Combine granulated sugar and orange zest in a large bowl; using your fingers rub the orange zest into the sugars until well combined and fragrant. Add all-purpose flour, baking powder, baking soda, salt, and pumpkin pie spice into the bowl and mix well to combine.
In a medium-sized bowl combine whole milk, pumpkin puree, orange juice, eggs, and vanilla extract; whisk well until completely smooth and combined. Gently fold the liquid mixture into the dry mixture, stirring with a rubber spatula until just combined.
Fold in melted unsalted butter, stirring just until butter is incorporated.
Divide batter evenly among muffin tins, filling each tin 3/4 of the way full. Sprinkle a little of the cinnamon sugar mixture on top of each muffin.
Bake until set in the center and golden brown; about 20-22 minutes.
Allow muffins to cool in the pan 5 minutes, then glaze and serve warm.
