Whisk together flour, baking soda, baking powder, salt, and pumpkin pie spice in a medium bowl until evenly distributed.
Beat softened butter, granulated sugar, and brown sugar in a large bowl on medium speed for about 2 minutes until pale, fluffy, and lighter in color. Scrape down the bowl halfway through.
Add pumpkin puree, egg yolk, and vanilla extract to the creamed butter mixture and beat on medium speed until fully combined, about 1 minute. The mixture may look slightly curdled, which is normal.
Add the dry ingredient mixture to the wet ingredients in two batches, mixing on low speed just until the flour disappears. Be careful not to overmix to avoid tough cookies.
Fold in the white chocolate chips with a rubber spatula until evenly distributed. Reserve a small handful to press onto the tops of the shaped cookies for a bakery-style finish.
Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes to firm up the butter and prevent spreading. For a faster alternative, chill in the freezer for 20 minutes.
Preheat your oven to 350°F while the dough chills. Line baking sheets with parchment paper or silicone baking mats.
Scoop dough into 1.5-tablespoon balls using a cookie scoop and place them 2 inches apart on the prepared baking sheets. Press a few extra white chocolate chips onto the top of each ball for visual appeal.
Bake for 10 to 12 minutes until the edges are set and the centers still look slightly soft. Rotate the pan halfway through if your oven has hot spots.
Let the cookies rest on the baking sheet for 5 minutes before transferring them to a wire cooling rack to cool completely. Enjoy warm with the chocolate still soft.