Preheat your oven to 160ºC (320ºF) and line a muffin tin with cupcake liners.

In a large mixing bowl, whisk together flour, baking powder, baking soda, pumpkin spice, and salt.

In a separate bowl, whisk together pumpkin purée, vegetable oil, eggs, and vanilla extract until smooth.

Gently fold wet ingredients into dry ingredients until no flour streaks remain, being careful not to overmix.

Fill cupcake liners about two-thirds full with batter using a large cookie scoop.

Bake for 23-24 minutes and check doneness with a toothpick; it should come out clean.

Cool cupcakes in the tin for about 5 minutes before transferring to a wire rack to cool completely.

For frosting, beat softened butter and brown sugar on high until light and fluffy, about 5 minutes.

Add cream cheese and vanilla extract, mixing until smooth and creamy.

Gradually mix in sifted powdered sugar until fully combined and desired consistency is reached.

Frost cooled cupcakes generously with the creamy brown sugar frosting and serve.