Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
Mix dry ingredients: In a medium bowl, whisk together flour, baking soda, and salt.
Mix wet ingredients: In a large bowl, combine melted butter, brown sugar, and granulated sugar. Beat until smooth. Add vanilla, egg, and egg yolk. Mix until creamy.
Combine wet and dry ingredients. Stir in chocolate chips.
Portion the dough: Scoop dough into rounded tablespoons and place 2 inches apart on the baking sheet.
Bake for 10–12 minutes until the edges are golden but centers look slightly underbaked.
Cool on the baking sheet for 2 minutes, then transfer to a wire rack.