Add the butter and sugar together in a stand mixer fitted with a paddle attachment and beat for about 3 - 4 minutes, or until light and fluffy.
Add in the egg and yolk, beat for another 2 minutes, or until light and fluffy.
Add in the cookie butter and vanilla, then beat until completely combined and light in color - another two minutes.
Mix together the flour, baking soda, and salt together in a small bowl. Stir into the butter mixture until just combined. Fold in the chocolate chips.
Cover and chill the dough in the refrigerator for about one hour. Create balls of dough that are about two tablespoons big, then top with the flaky sea salt if using.
Preheat the oven to 350 F. Line two baking sheets with parchment paper or silicone baking mat.
Bake for about 8 - 10 minutes, or until the edges are a light golden brown. Allow them to cool on the baking sheet for about 2 - 3 minutes.