Preheat oven to 400 degrees. Line a 6 muffin tin with paper cups. Spray the cups with nonstick spray.
In a large bowl, combine flour, baking powder, salt, pumpkin pie spice, and ⅔ C sugar. Stir together well and set aside.
In a small bowl, whisk the egg until frothy. Add the oil and vanilla and whisk together. Pour the egg mixture into the flour mixture. Add the pumpkin puree. Fold together about 15-20 strokes until combined. Fold in the chocolate chips, reserving about 1 tablespoon for topping the muffins.
Scoop the batter into the prepared muffin tin. Fill the cups to the top.
In a small bowl, combine ½ c sugar and cinnamon. Sprinkle on top of muffin batter in pan. Sprinkle the reserved chocolate chips on top.
Bake in preheated oven for 2 minutes. Reduce temperature to 375 degrees and cook an additional 26 minutes until the tops spring back when gently poked.
Remove from oven and turn out onto wire rack to cool.
Store in an airtight container in the refrigerator for 2-3 days.