For The Cookies:

• Preheat oven to 375°F.
• In a mixing bowl, whisk together flour, baking powder, baking soda, cinnamon, ginger, nutmeg and salt, set aside.
• In the bowl an electric stand mixer fitted with paddle attachment and set on medium speed, whip together butter, light-brown sugar and granulated sugar until pale and fluffy, about 3 – 4 minutes. Add in eggs one at a time, mixing after each addition until combine. Mix in sour cream and vanilla extract, then mix in pumpkin puree.
• With mixer set on low speed, slowly add dry ingredients and mix until combine.
• Transfer 1 ½ cups of the cookie dough to a pastry bag fitted with a 1/2-inch plain tip and pipe 2 inch rounds onto a Silpat or parchment paper lined cookie sheet, spacing cookies at least 2 inches apart.
• Bake in preheated oven about 10 minutes until tops spring back when touched.
• Allow to cool several minutes on baking sheet before transferring to a wire rack.
• Cool completely then prepare icing and spread icing over cookies.

For The Frosting:

• Measure 4 cups of powdered sugar into a mixing bowl, set aside.
• Brown butter in a small saucepan over medium heat, swirling pan occasionally (butter will melt, after a few minutes it will splatter, then it will foam, then golden brown flecks will begin to appear in the center of the foamy bubbles. This is when you remove it from heat.
• Carefully pour browned butter over powdered sugar in mixing bowl, use a rubber spatula to scrape any excess butter and browned bits from pan. Add half and half and stir mixture until smooth.
• Frost the cookies. While frosting, add additional half and half, about 1 – 2 teaspoon at a time, to icing mixture to thin as it will thicken as it sits.