In a large bowl, allow filtered bacon grease to come to room temperature along with the butter.
¼ cup Bacon Grease, ¼ cup Unsalted Butter
Add white and brown sugars to the butter and bacon grease. Cream them together until they are light and fluffy.
½ cup White Sugar, ¼ cup Brown Sugar
Add the egg and vanilla, lightly incorporate these two ingredients. Don't get to crazy stirring the egg in or your cookies will be a tough.
1 Large Egg, 1 teaspoon Vanilla Extract
Add carefully measured all-purpose flour to the cookie mixture. When measuring flour make sure you stir the flour and never tap it or shake it. It should be measured with very light hands. Also add baking soda and salt.
1 ½ cups All Purpose Flour, ½ teaspoon Baking Soda, ½ teaspoon Kosher Salt
Stir just until the dry ingredients are mixed in. Fold in semi-sweet chocolate chips.
1 cup Semi-Sweet Chocolate Chips
Scoop walnut-sized scoops of dough (maybe ping pong ball sized for those who need a different visual) onto the cool baking sheet.
Leave plenty of room for the cookies to spread--3 cookies to a row is usually about right for most people's cookie sheets.
Bake for 10-12 minutes or until cookies are golden brown.
Allow cookies to set on the cookie sheet for 1-2 minutes to firm up before removing them to a cooling rack.
Notes
I often stir my cookie dough by hand using a wooden spoon so I have better control over the amount of stirring. If you must use a mixer and paddle attachment, mix on low. And note, the amount of mixing should be minimal when adding the egg, flour, and chocolate chips to ensure a tender cookie.
Ensure the baking sheets are cool when scooping dough onto them to prevent cookies from spreading out before they enter the oven. I find it helpful to rotate 2 cookie sheets, allowing 1 to cool while the second batch bakes.