Using a hand mixer or stand mixer, cream together shortening and brown sugar until smooth and fluffy
Beat in eggs and vanilla extract.
In a separate bowl, whisk together flour, baking soda, baking powder, cream of tartar and salt.
Slowly mix flour into shortening on low speed until just blended together.
Fold in chocolate chips.
Cover bowl with plastic wrap and refrigerate 1 hour or up to 12 hours.
Remove dough from fridge and allow to sit at room temperature for 5 minutes before handling.
Preheat oven to 350°F and line a baking sheet with parchment paper.
Using a cookie scoop or tablespoon, scoop dough and shape into evenly sized balls.
Place dough balls on prepared baking sheet about 2 inches apart
Bake in preheated oven for 8-10 minutes. Cookies will still be slightly wet in the centre
Allow to cool on baking sheet for 2 minutes before transferring to a cooling rack
Once cooled, store in an air tight container.