In a medium bowl, cream together 4 tablespoons of unsalted butter and 1/4 cup of brown sugar until light and fluffy.

Gradually mix in 1/4 cup of all-purpose flour, 1 teaspoon of pumpkin pie spice, and a pinch of salt until the mixture resembles coarse crumbs.

Chill the streusel in the refrigerator for about 30 minutes while you prepare the cookie dough.

While the streusel chills, place 1/2 cup of canned pumpkin puree on paper towels to remove excess moisture.

In a separate bowl, whisk together 1 1/2 cups of all-purpose flour, 1 teaspoon of baking powder, 1/2 teaspoon of baking soda, 1 teaspoon of pumpkin pie spice, and 1/4 teaspoon of salt.

In a large bowl, beat 1/2 cup of softened unsalted butter and 1 cup of brown sugar until light and fluffy.

Add 2 egg yolks and 1 teaspoon of vanilla extract, mixing thoroughly.

Gently fold in the prepared pumpkin puree.

Gradually add the dry mixture to the wet ingredients and mix until just combined.

Drop rounded portions of cookie dough onto a lined baking sheet, spacing them about 2 inches apart.

Preheat your oven to 350°F (175°C). Bake for 11 to 12 minutes.

Remove from oven and cool on a wire rack for about 10 minutes.

Prepare the glaze by whisking together 1 cup of powdered sugar, 2 teaspoons of vanilla extract, and enough whole milk.

Drizzle the glaze over the cookies once cooled.