To prepare a oatmeal chocolate chip cookies, the best cookies recipe. Preheat the oven to 325 degrees F. Line two cookie sheets with parchment paper. Cream the butter and sugar with an electric mixer on medium speed until light and fluffy, about 2 minutes. Add the egg and vanilla and beat until combined. Gradually add the flour and mix until just combined, scraping down the sides of the bowl as needed. Fold in the chocolate chips. Press the mixture into the greased and floured cookie sheet. Bake for 12 to 15 minutes or until the edges are brown and the center is set. Let the cookies cool on the baking sheet for 5 minutes before transferring to wire racks to cool completely.