Instructions

1. If you are using a stand-up mixer, use the paddle attachment to mix the batter. In the mixing bowl, beat butter and shortening together until well combined. Add brown sugar and white granulated sugar and beat on medium-high speed until light and fluffy. Next, add the egg, egg yolk, and vanilla and beat until light and fluffy. About 5 minutes. If you are using a hand electric mixer, beat a few minutes longer.
2. Scrape down the sides of the bowl. In another bowl combine the flour, baking soda, salt, and cornstarch together. Add the dry four ingredients to the wet (sugar) ingredients and mix until just combined. About 1 minute.
3. Using a sturdy wooden spoon, stir in the chocolate chips and Snicker bar pieces. Mix by hand. (Note: Batter will be thick)
4. Using a medium 2-inch cookie scoop, scoop about 26 mounds of cookie dough on a large tray or plate. Cover with plastic wrap and refrigerate for at least two hours or overnight. ( Note: dough can be refrigerated for up to 5 days before baking and can be frozen for up to 2 months) Don’t bake warm cookie dough because cookies will be flat and will spread out too much. Plus chilling the dough allows the flavors to soak up and gives you a better tasting cookie, I think.
5.  Once you are ready to bake, preheat your oven to 350 degrees. Line a cookie sheet pan with parchment paper, baking matt, or spray with a nonstick spray. Roll cookie dough up and shape into a cone shape about 1 ½ inches high. (See photo in the blog post above.) Place cookie mounds about 2-inches apart and bake for 7 to  8 minutes. The center should be a little gooey. Be careful not to over-bake because the cookies will set and continue to bake after taking them out of the oven. 
6. Allow the cookies to cool and set on the cookie sheet for about 3 to 4 minutes and then gently transfer them to a wire rack to continue cooling. 
7. Store cookies in an airtight container for up to 6 days at room temperature. Cookies will freeze for up to 2 months. Enjoy with a cold glass of milk!