Using an electric mixer, cream shortening, butter and white sugar together until light and fluffy.
Beat in egg, chocolate syrup and vanilla extract. Set aside.
In a separate bowl, whisk together flour, cocoa powder and baking soda.
Add flour mixture to sugar mixture and beat on low speed until flour is just blended in.
Fold in chocolate chips.
Cover bowl and refrigerate for minimum 2 hours or up to 12 hours.
Remove dough from fridge after chilling and allow to rest at room temperature for 5 minutes before handling.
Meanwhile, preheat oven to 350°F and line cookie sheets with parchment paper.
Scoop cookie dough onto prepared cookie sheets, making scoops as even as possible. (you should have 24 evenly sized spoonfuls)
Bake in preheated oven for 10-12 minutes. Cookies should still be glossy in the centre, they will continue cooking on the cookie sheet while cooling.
Cool for 5 minutes on cookie sheet before transferring to a cooling rack.
Store cookies in an airtight container for up to 5 days.
