Preheat oven to 350 degrees F (175 degrees C).

Grease 36 muffin cups.

In a large bowl, whisk together self-rising flour, 2 1/2 cups white sugar, and pumpkin pie spice.

Add pumpkin puree, eggs, and vegetable oil to the dry ingredients.

Stir until the batter is smooth.

Scoop the batter into the prepared muffin cups.

In a small bowl, stir together 2 tablespoons white sugar and ground cinnamon.

Sprinkle the cinnamon sugar mixture over the muffins.

Bake in the preheated oven until the muffins are lightly golden brown and a toothpick inserted into the center comes out clean, about 20 minutes.