• Preheat oven to 350°F. Line two cookie sheets with a silicone baking mat.
• Using a standing mixer with paddles attached, cream the butter, sugar, light brown sugar, eggs, corn syrup, and vanilla until light and fluffy, about 5-7 minutes.
• In a medium bowl, whisk the flour, cocoa powder, cornstarch, salt, and baking soda.
• Gradually beat the dry ingredients into the wet until a dough forms.
• Using a medium cookie scoop, scoop out dough mound into your hand and roll into a ball. Place onto the cookie sheet and light press into a thick disk.
• Bake in the preheated oven for 15-18 minutes or until firm around the edge.
• Allow to cool for a few minutes on the baking sheet. Then move the cookies to a cooling rack to cool completelly.

To make the vanilla frosting

• Use a standing mixer with paddle attachment, beat the butter, powdered sugar, vanilla, and whipping cream until combined, smooth and holds a peak.
• Scoop the frosting into the piping bag. Pipe a tight spiral onto the top of the cookie.
• Sprinkle chopped heath bars on top of each cookie.