Preheat oven to 350 degrees. Line baking sheet with parchment paper or use baking stone.
Melt butter in microwave. I put mine on the "melt butter" setting and it will be not all fully melted, but close enough.
Using an electric mixer add granulated and light brown sugars to the butter. Mix until combined (about 1 minute). Add egg and vanilla and mix for a few seconds more.
Add salt, baking soda, and flour. Mix on low speed until combined. You will know when your dough is ready because it will pull slightly away from the sides.
Fold in mini, semi-sweet, and dark chocolate chips into the dough. Do not use the electric mixer for this because it will tear up your chips. You want to be able to see the 3 different sizes.
With 2-inch scooper, add the dough to the cookie sheet or baking stone. Cookies should be about 2 inches apart from one another. Press down slightly with fingers to flatten.
Bake for 13-15 minutes. Cookies are done when they are still puffy in the center and have a little gold coloring on the edges.
Allow to cool on baking sheet or stone for 10 minutes before transferring to cooling racks or mouths. Enjoy!