Preheat your oven to 350°F and line a baking sheet with parchment paper or silicone baking mat.
In a small, microwave-safe bowl, microwave butter for 20 to 30 seconds, until mostly melted. Set aside to cool.
In a small bowl, whisk together flour, baking soda, salt, and spices. Set aside.
In a medium bowl, combine melted butter, granulated sugar, and brown sugar, and whisk until well-combined. Add egg yolk, canned pumpkin, and vanilla extract and whisk until smooth.
Use a spoon to stir in flour mixture until just combined. Scoop 1 1/2-ounce scoops of dough (this should make 8 cookies) and place on a cookie sheet (for the roundest cookies, roll your dough into a ball before placing on the sheet). Use the palm of your hand to smash the dough to 1/2-inch thickness.
Bake for 8 to 11 minutes, until the tops of the cookies look set and the bottoms are just slightly browned. Cool completely before frosting.
Cream Cheese Frosting
In a medium bowl, combine softened cream cheese, butter, and vanilla extract. Beat until smooth.
Add powdered sugar and pinch of salt and beat until frosting is smooth, scraping the bottom of the bowl to make sure all of the sugar is incorporated. If the frosting is too thick, add milk by the half teaspoon until frosting is creamy and smooth.
Frost on cooled cookies. Sprinkle with cinnamon sugar or sprinkles if desired. Serve and enjoy!
Notes
*You can use salted butter in this recipe (cut the salt in half in the cookies and omit the extra pinch of salt in the frosting), but some people find frosting made with salted butter to be too salty.*Correct flour measurement is very important in this recipe. For best results, measure by weight or the Spoon and Sweep Method (stir the flour in your container to fluff it up and then spoon it into your measuring cup, sweep excess off with the flat of a knife).* You can replace the spices (not the salt) in the cookies with 3/4 teaspoon pumpkin pie spice.