Preheat oven to 375°F if baking immediately (although a dough rest is strongly recommended).
Using a mixer, cream butter, butter-flavored shortening, white sugar and brown sugar on medium to medium-high speed for 3-5 minutes until mixture is pale and fluffy.
While your mixture is creaming, in a separate bowl, whisk together flour, baking soda and salt.
Add eggs and vanilla to creamed mixture and mix until fully incorporated.
Slowly add the flour mixture to the creamed mixture, mixing on low to incorporate.
Stir in chocolate chips by hand to avoid breaking up the chocolate chips.
Recommended for best flavor: If time permits, transfer dough to a bowl that can either be covered by a lid or plastic wrap, or transfer to a gallon-sized baggie and store in the fridge for 24 hours or overnight. Maximum flavor is achieved at 1 day but the dough will store up to 2-3 days.
Heat oven to 375°F. Scoop dough into 1 or 1 ½ Tablespoon-sized cookies with a cookie scoop or scoop with a spoon and roll into a ball. Place dough on an ungreased baking sheet about 2 inches apart.
Bake 1 Tablespoon-sized cookies for 8-10 minutes. Bake 1 ½ Tablespoon-sized cookies for 10-12 minutes. Fully-baked cookies will brown slightly along the bottom edge, but for maximum softness and chewiness, don't let them brown on top.
Let cool 2 minutes before removing to wire cooling rack.