Preheat your oven to 160ºC (320ºF) and line a 12-cup muffin tin with cupcake liners.

In a large bowl, whisk together all-purpose flour, dark brown sugar, baking powder, baking soda, pumpkin spice, and salt.

In another bowl, combine pumpkin purée, vegetable oil, eggs, and vanilla extract, whisking until smooth.

Pour the wet ingredients into the dry ingredients and gently stir until just incorporated.

Evenly distribute the batter into the cupcake liners, filling each about two-thirds full.

Bake for 23-24 minutes or until a toothpick inserted comes out clean.

Allow the cupcakes to cool in the tin for 5 minutes, then transfer them to a wire rack.

For the frosting, cream softened butter and dark brown sugar for about 5 minutes.

Add cream cheese and vanilla extract, mixing until smooth, then gradually add the powdered sugar.

Frost the cooled cupcakes using a piping bag and decorate as desired.