Preheat the oven to 350°F convection (with fan) or 375°F conventional (no fan). Then, line 2 muffin pans with paper liners. If your muffin tins are nonstick, you can also just spray them with nonstick cooking spray. 

In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, kosher salt, and pumpkin spice. 

In a separate large bowl, place your eggs and whisk them to break up the proteins.

Slowly pour the vegetable oil into the eggs while you whisk. This is where you create the emulsification.

Add the light brown and granulated sugar to the oil and egg mixture and whisk until no sugar lumps remain and the mixture is fully emulsified.

Whisk in the pumpkin puree. Stir the flour mixtures into the wet ingredients. Mix until just combined.

Divide the pumpkin batter between the liners in the muffin pan. Then top with a few pepitas (optional).

Bake in the preheated oven until a toothpick or cake tester comes out clean and the muffins spring back when touched lightly. This will take about 20 minutes, but they will bake faster in a convection (with fan) oven. Allow to cool for 5 minutes before removing to a wire rack to cool completely.