Step 1: Preheat the Oven - Start by preheating your oven to 350°F (175°C) for even baking.
Step 2: Cream the Butter and Sugars - In a large mixing bowl, combine the softened butter, granulated sugar, and brown sugar. Cream until light and fluffy, about 2-3 minutes.
Step 3: Add the Eggs and Vanilla - Add the egg, egg yolk, and vanilla extract to the butter mixture. Beat until well combined.
Step 4: Combine Dry Ingredients - In a separate bowl, whisk together the flour, baking soda, and salt.
Step 5: Mix Dry Ingredients into Wet Ingredients - Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined.
Step 6: Fold in the Chocolate Chips - Gently fold in the chocolate chips until evenly distributed.
Step 7: Scoop the Dough - Portion out the cookie dough onto ungreased baking sheets, spacing them about 2 inches apart.
Step 8: Bake the Cookies - Bake for 10-12 minutes, until edges are lightly golden and centers look soft.
Step 9: Cool the Cookies - Let cool on baking sheets for about 5 minutes before transferring to a wire rack.