For the muffins: Preheat the oven to 400°F. Generously grease a 12-cup muffin tin.

In a large bowl, sift the flour, sugar, baking powder, cinnamon, ginger, nutmeg, and salt. Cut in the butter using two knives or a pastry cutter until it is fully incorporated.

In a separate bowl, mix together the pumpkin puree, evaporated milk, egg, and vanilla. Pour the pumpkin mixture into the flour mixture. Add the raisins, if using. Fold gently until the mixture is just combined.

Pour the batter into the greased muffin tin (the batter hardly ever fills all twelve unless you fill the cups half full).

For the topping: In a small bowl, combine the sugar, cinnamon, and nutmeg. Sprinkle all over the top of each unbaked muffin.

Bake until golden brown, 20 to 25 minutes. Allow the muffins to cool in the pan for 10 minutes, then remove them from the pan to cool completely.

For the frosting: In the bowl of an electric mixer, combine the butter, cream cheese, powdered sugar, and vanilla. Mix on high until soft and whipped. Spread onto completely cooled muffins, or place into a large pastry bag with a large star tip and go crazy! Store in the fridge, as icing will soften at room temperature.