Preheat oven to 350 F.
Melt butter over medium heat in a small skillet or heavy-bottomed pot.
Continue to heat the butter, stirring periodically, until it turns brown (10-15 minutes).
The butter will first boil with big bubbles (it’s not done then). Then, the bubbles will get smaller. Turn up the heat slightly and monitor closely until the butter looks more brown (that’s when it’s done).
Remove butter from heat and cool to room temperature.
In a medium-sized mixing bowl, mix cooled brown butter, brown sugar, and granulated sugar until just combined.
Mix in the eggs.
Mix in the vanilla, flour, baking soda, and salt until just combined.
Fold in the chocolate chips.
Fill 12 cupcake liners in a cupcake tin almost to the top with cookie dough.
Divide the remaining dough into 12 evenly sized balls, slightly flatten them, and space them out loosely on a cookie sheet.
Bake cupcakes for 25 minutes or until tops just begin to get dark brown. Cool in cupcake tins.
Bake cookies for 15 minutes or until edges just begin to get dark brown. Cool on a cooking rack.