These Chocolate Mint Surprise Cookies remind me of a cookie version of York Peppermint Patties. It has a delicious, chocolate cookie base, topped with a minty cream center and topped with chocolate.
Preheat oven to 350 degrees. Use parchment paper or a silpat mat to line a baking sheet.
Cream the butter, shortening, and sugar in a stand mixer until light and fluffy (about 2-3 minutes). Scrape the sides of the bowl to make sure all ingredients are blended. Beat in egg, milk and vanilla.
Combine the flour, cocoa, baking powder, salt and cinnamon in medium bowl and them gradually add this dry mixture to the butter sugar mixture. Mix until the flour is all incorporated but don't overmix. Shape dough into a disc and wrap tightly in plastic wrap and refrigerate for 6 hours or freeze for 1 1/2 hours.
On a lightly floured surface, roll out the dough to about 1/8-in thickness. Using a 1" round cookie cutter, cut out cookie circles using all the dough. NOTE: If you'd like bigger cookies, just use a bigger cookie cutter. Place the cookie dough circles on the prepared baking pans (12 cookies to a sheet).
Bake at 350 degrees for 8-9 minutes. Cool on baking sheet for 2 minutes before removing to wire racks to cool completely.
Combine all the peppermint layer ingredients (confectioner's sugar, corn syrup, butter and peppermint extract) in a large bowl. Mix until smooth. Shape the peppermint mixture into small balls (about 1/2" each) and place on each cookie. Flatten the peppermint ball with your hand to almost cover the cookie. Repeat with all the cookies. Place on waxed paper lined baking sheets and refrigerate for 30 minutes.
In the microwave, melt the chocolate chips and shortening for 30 seconds at a time. Stir in between. Do 30 second heating increments until the chocolate is melted and smooth. Spread about 1 teaspoon of melted chocolate over each cookie. Chill cookies until firm and enjoy.