Preheat oven to 325°F. Line a cookie sheet with parchment paper.
Melt the butter in the microwave and let cool for 15 minutes.
1/4 cup butter
In a large bowl, whisk melted butter, brown sugar, and sugar. Add in vanilla and egg. Whisk until smooth.
1/3 cup light brown sugar, 1 tbsp white sugar, 1 egg yolk, 1 tbsp vanilla
Add in flour, baking soda, and salt. Use a rubber spatula and fold the dough until just combined. Do not over mix! Add in dark and semi-sweet chocolate chips and fold into dough.
2/3 cups all-purpose flour, 1/4 tsp baking soda, 1/4 tsp salt, 1/4 cup semi-sweet chocolate chips, 1/4 cup dark chocolate chips
Scoop 3 cookie dough balls and place on the prepared cookie sheet.
Bake for 13-16 minutes. Mine took 16 minutes. The cookies will be ready when the edges are a golden brown, but the inside will look very soft. Remove from oven and sprinkle a dash of sea salt if desired. Let the cookies cool on the hot pan for a few minutes before serving warm or cool completely and enjoy!