In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, about 2-3 minutes.

Add in the egg, creamy peanut butter, and vanilla extract, mixing until fully combined.

In a separate bowl, whisk together the all-purpose flour, cornstarch, baking soda, baking powder, and fine sea salt.

Gradually add the dry ingredients to the wet mixture until just combined.

Cover the bowl with plastic wrap and refrigerate for at least 1 hour.

Preheat your oven to 375°F (190°C).

Scoop the dough and roll it into balls, approximately 1 tablespoon each, and place them onto a baking sheet lined with parchment paper.

Bake for 8-10 minutes, or until the edges are set but the centers are still slightly soft.

Let cookies cool completely on a wire rack.

For the frosting, beat the softened butter until creamy, then gradually add the powdered sugar, milk, and vanilla extract.

Add purple gel food coloring and mix until fluffy and hold piping consistency.

Once cookies have cooled, pipe the frosting around the edges of each cookie.

Press a chocolate Kiss or Hug into the center of each frosted cookie.

Sprinkle Halloween-themed decorations or sanding sugar around the brim of the frosting.

Allow decorated cookies to sit at room temperature until frosting sets, about 30 minutes.