Preheat oven to 350 degrees.
Using a stand mixer fitted with the paddle attachment or a hand mixer, cream the shortening and brown sugar on high for 1-2 minutes. Scrape down the bowl once complete.
Add in milk, eggs and vanilla extract. Mix until combined. Scrape down the bowl once complete.
In separate bowl, whisk dry ingredients together (flour, baking soda, salt).
Add dry ingredients to wet ingredients in 4 portions. Mix until combined
Using a wooden spoon, mix in the chocolate chips.
Thoroughly grease a pan and evenly spread the cookie dough throughout the pan. *See notes for pan sizing*
Bake for 10-25 minutes, or until the edges have browned and the middle is light in color but not jiggly. *Total time depends on the cake size.
Let the bars cool completely before cutting & serving.