Preheat your oven to 350°F (175°C) and line a muffin pan with 15 muffin liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and spices (cinnamon, ginger, nutmeg, and cloves). Set this mixture aside.

In a large bowl, stir together the pumpkin puree, oil, brown sugar, eggs, and milk.

Gradually add the dry mixture to the wet mixture, stirring until just combined.

Spoon the batter into the muffin cups, filling each one about two-thirds full.

Bake the cupcakes for 20 minutes, or until a toothpick inserted into the center comes out clean. Let them cool for 10 minutes.

Transfer the cupcakes to a wire rack to cool completely.

To make the frosting, beat the butter until fluffy. Then add cream cheese, vanilla extract, and cinnamon, and continue to beat until smooth.

Slowly add the powdered sugar and mix until everything is fully combined and fluffy.

Frost the cooled cupcakes using a flat knife or a piping bag.