Line a cookie sheet with parchment paper and set aside.

Melt the butter in a microwave safe bowl or over low heat in a skillet until just melted, but not hot.

Add the melted butter, brown sugar, and white sugar to a medium-sized mixing bowl. Use a whisk to mix the butter and sugars until fully incorporated, about 30 seconds.

Add the egg yolk and vanilla to the bowl and whisk until well mixed.

Pour the flour, baking soda, and salt into the mixing bowl. Use a rubber spatula or wooden spoon, to gently fold the dry ingredients into the wet ingredients until almost fully combined, but some streaks of flour are still visible.

Sprinkle in the chocolate chips and gently stir until the chocolate is evenly distributed and no streaks of flour remain.

Scoop out the dough about 2 tablespoons in size and place on the prepared cookie sheet.

Allow the cookie dough to sit at room temperature for 20 minutes to firm up. While your cookies are resting, preheat the oven to 375 degrees F, and place your oven rack in the middle position.

Once rested, bake the cookies for 8-11 minutes until lightly golden brown around the edges and puffed in the center. The centers should look slightly underbaked and doughy, but not raw.

Remove the cookies from the oven and let them sit on the pan for 10 minutes to fully set before transferring to a cooling rack or a serving plate.