- In a medium-sized mixing bowl, sift or whisk the 1 teaspoon baking soda, 1 teaspoon cream of tartar , 1/2 teaspoon  salt  and 4 cups all-purpose flour  
- In a large mixing bowl or the bowl of a stand mixer, cream together the 1  cup unsalted butter, 1/4 cup shortening, 1 cup granulated sugar  and 1 cup brown sugar, until light and fluffy. 
- Add in the 2  large  eggs, beaten, followed by the 1 teaspoon vanilla extract  
- Add in the sifted dry ingredients, followed by the 6 butter brickle candy bars (such as Heath bars),  crumbled.   
- Form dough into logs, around 2" in diameter. Wrap logs of dough in either plastic wrap or parchment paper. Refrigerate overnight (or freeze if not planning to bake right away). 
- Slice dough 1/4" thick; place on lined baking sheet and bake @350°F 10-12 minutes (increase baking time by 2 minutes if baking from frozen state). * Cool cookies on wire rack and store in airtight container.