In the bowl of a stand mixer, combine 3 cups all-purpose flour, 3/4 cup dark brown sugar, 2 tablespoons ground pumpkin pie spice, 3/4 teaspoon baking soda, and 1/2 teaspoon salt at low speed until combined. Stop the mixer and add the 12 tablespoons unsalted butter. Mix at medium-low speed until the mixture is sandy and the dry ingredients are coated in butter, about 1-2 minutes. Reduce the speed to low and, with the mixer running, gradually add the 1/2 cup molasses and 2 tablespoons heavy cream. Mix until the dough is evenly moistened, about 20 seconds. Increase the speed to medium and mix until thoroughly combined, about 10 seconds.
Transfer the dough to a large piece of plastic wrap, shape into a disk, wrap tightly and freeze until firm, 20 to 30 minutes. Alternatively, refrigerate the dough 2 hours or overnight.
To bake, preheat the oven to 350 degrees F. Line baking sheet with parchment paper.
Roll chilled dough into tablespoon sized balls. Roll each dough ball in the 1/2 cup granulated sugar first until coated and then roll again in 1/2 cup confectioners' sugar until coated evenly. Place the sugar coated dough balls 1-inch apart from each other on the prepared baking sheet.
Bake the cookies until set in the centers, 10 to 12 minutes. Remove from the oven when they start to crack. Do not over bake. Cool the cookies on the sheets 2 minutes, then remove the cookies to a wire rack to cool to room temperature.