Preheat the oven to 375F . In a stand mixer with the paddle attachment and beat butter, Crisco shortening and sugar together until light in color and fluffy. Add in the egg whites and yolk one at a time and mix until incorporated between each egg white. If using, add the vanilla.
In a small bowl, whisk together the flour, salt, and baking soda. Slowly add the flour mix, about a quarter cup at a time, to the bowl while the mixer stirs at a low speed. Right before adding the last bit of flour, add the chocolate chips. The dough should be thick and not stick readily to the sides of the bowl.
Separate the dough into separate, smaller bowls. I divided MY batch into 5 different bowls, about one to two cups of dough in each bowl, and each bowl produced 5-8 cookies.
For the ombre effect, leave one bowl of dough plain. Use a tablespoon to measure out dollops of dough. Arrange the plain dough balls on a cookie sheet lined with parchment or a silicone mat. Bake for 8-10 minutes - check these carefully and note the time they finish cooking. They should be cooked through but not yet browning. The cookie should not appear moist in the center when they are finished cooking.
In the other bowls of dough, add a few drops of food coloring to each ball of dough until the desired colors are achieved. I used a combination of pink, red, and burgundy gel colors - starting with 1-2 drops in the first for light pink; 3-4 drops pink plus one drop red for second; 3-4 drops pink plus 2-3 drops red for third; 1-2 drops red plus 1-2 drops burgundy for the fourth. You may need to adjust the amount of food coloring for each cookie, depending on the type of food coloring you are using.
Based off the cooking time for the plain batch of cookies, form dough balls from the remaining dough and cook in batches for 8-10 minutes, or about the same amount of time for the first batch. Let the cookie finish cooking on the baking sheets 2-3 minutes once out of the oven and then transfer to a cooling rack. Serve warm or room temperature. Enjoy!