Cook butter in a pan with medium heat. It will be sizzle and bubbly from the water content. After the moisture and the sound of the sizzle are gone, wait for 1-2 minutes until the milk solids from the butter turn brown, and turn off the heat. Don't let the pan unattended or you will end up with burnt butter instead of brown butter. Transfer it to a heatproof bowl. Set aside and let cool.
Sift flour and baking soda into a bowl. Set aside.
After the browned butter is cooled, whisk browned butter, brown sugar, white sugar, egg, vanilla, and salt with a mixer for about 2-3 minutes until the mixture is fluffy.
Add 1/3 of the flour mixture and whisk with a mixer until just combined. Add the rest and whisk again until combined.
Add chocolate chips then stir with a spatula until combined.
Preheat oven to 350ºF or 175°C. Divide every 1 teaspoon of dough for each cookie then place them on a baking tray lined with parchment paper. Put the cookie dough balls 2 inches from each other so they will not stick when baked.
Bake for 10 minutes until golden brown. Cool the cookies completely before removing them from the parchment paper.
Mini chocolate chip cookies are ready to serve. Enjoy!