Preheat oven to 350 degrees. Lightly grease a mini muffin pan.
Cream the brown sugar, brown sugar and granulated sugar in a stand mixer until light and fluffy. Scrape the sides of the bowl to make sure all ingredients are blended.
Add in the egg and vanilla and beat until combined.
Add in flour, cornstarch, baking soda, and salt. Mix until all combined.
Add in the mini chocolate chips and blend for a few seconds until just combined.
Scoop about 1 TBSP of cookie dough into each mini muffin space. 11. Bake for 8-10 minutes. Immediately after removing from oven, lightly press a mini Snickers square into each cookie until level with top of cookie. Allow cookies to cool on the pan for 5-10 minutes before transferring to a cooling rack. Cool cookies completely.
CARAMEL BUTTERCREAM FROSTING
In stand mixer, cream butter until smooth.
Add in the vanilla, caramel and powdered sugar and mix on high for about 2-3 minutes until smooth. If the frosting is too thick, add heavy cream a teaspoon at a time to get the consistency you are looking for. If frosting is too thin, add more powdered sugar.
Put the frosting in a piping bag with a round tip OR you can put the frosting in a gallon size Ziploc bag and cut off one corner of the bag. Use the frosting bag to pipe frosting in a spiral on top of the cooled cookies. Sprinkle each cookie with sea salt.