In a large mixing bowl, cream the butter and sugar. Then, beat in the vanilla, egg, egg yolk, baking soda, and salt. Next, beat in the flour. Stir in the chocolate chips. Cover and refrigerate dough for at least 30 minutes.
Preheat the oven to 350 degrees. Line a baking sheet with parchment paper. Scoop dough into rounded spoonfuls, placing about 2 inches apart. Bake for 11-13 minutes, until beginning to brown on the edges.