Preheat oven to 325 degrees. Line a cookie sheet with parchment paper. {I use these parchment sheets- love them!}
Cream together the butter and shortening. Add in sugars and eggs and mix once more. Add in 1/2 the flour, the baking soda, baking powder and salt. Mix well. Add in remaining flour and mix until combined. Stir in chocolate chips.
Making the tiny cookies: I tested out sizes and to make the mini cookies like the ones in my photos, you need only 1/2 teaspoon of dough for each cookie. Yep- just that small amount! There are 2 ways I found you can easily do this: The first is to spray a 1 tsp measuring spoon with non-stick spray and scoop out dough, then divide it in half. This actually works pretty well, you'll just have to re-spray the spoon after 4 or 5 scoops. The second way is to scoop out dough using a regular 1.5 TBSP cookie scoop. (I use this cookie scoop here) Then divide that scoop of dough in half, then divide those 2 halves in half (so now you have 4 mounds of dough). Now divide all those dough mounds in half- you'll end up with 8 pieces of dough.
Roll mini dough into a ball and place on the cookie sheet. Bake for 6-8 minutes.
Once baked, transfer to a cooling rack.
Recipe yields 85-90 mini cookies (when you use 1/2 tsp of dough).