Prepare the streusel topping by mixing chilled unsalted butter and brown sugar until creamy, then add flour, pumpkin pie spice, and a pinch of salt to create a crumbly texture. Refrigerate while making cookie dough.

Dry the pumpkin by spreading it on a paper towel-lined surface and pressing with more paper towels until reduced to about 1/4 cup.

Mix flour, baking powder, baking soda, pumpkin pie spice, and salt in a bowl. In another bowl, cream butter and sugar until fluffy, then beat in egg yolks and vanilla, fold in dried pumpkin, and combine with dry ingredients.

Preheat oven to 350°F (175°C). Scoop dough into tablespoon-sized balls on a lined baking sheet, indent each ball, and top with streusel.

Bake for 11-12 minutes or until edges are golden but centers are soft. Reshape if necessary and cool on the baking sheet for 10 minutes before transferring to a wire rack.

In a small bowl, whisk powdered sugar, vanilla extract, and milk until smooth, adjust milk for desired thickness, then drizzle over cookies after they cool.