Melt your butter in the microwave for about 40 seconds (it won’t be fully melted)
Cream together the butter and sugars for about two minutes till light and creamy.
Add in the egg yolk, vanilla, and pumpkin purée. Stir till just combined.
Stir in the baking soda, salt, flour, cinnamon, and pumpkin pie spice.
Fold in the white chocolate chips.
Cover the dough and refrigerate for one hour, up to overnight.
Scoop the cookie dough into 2-2.5TBS sized balls. Roll into balls and place on a lined cookie sheet.
Slightly flatten each cookie dough ball.
Place pan into the oven and bake for 12-14 minutes, until cookies look set in the edges and mostly set in the middle.
Allow cookies to rest on the cookie sheet for another 3 to 4 minutes as they continue cooking on the pan.
Place a few extra white chocolate chips on the top of each cookie for looks, if desired.
Remove from pan to a cooling rack and cool completely.