Preheat the oven to 350 degrees and line a baking sheet with parchment paper.
In a mixing bowl, beat the softened butter and granulated sugar until smooth.
Add the pumpkin puree, egg yolk, and vanilla extract, then stir until combined.
In the same bowl, mix in the flour, baking powder, cinnamon, and salt until a soft dough forms.
Lightly flour a surface and roll the dough to about 1/4 inch thick.
Use a ghost-shaped cookie cutter to cut out shapes and place them on the baking sheet.
Bake for 10 to 12 minutes until the edges are lightly golden, then let the cookies cool completely on the sheet.
In a small bowl, stir the powdered sugar with the milk until smooth to make the icing.
Spread the icing over the cooled cookies and press two mini chocolate chips into each one as eyes.