Place the butter in a small sauce pot over medium heat. Watch the butter as it melts and simmers, stirring occasionally. Once the butter particles in the bottom of the pot have turned a dark teddy bear brown, and the butter is light brown, turn off the heat. It should smell nutty, not burnt. Place the butter in the refrigerator until in has solidified again.
Preheat the oven to 350 degrees F. Line several baking sheets with parchment paper. Scrape the firm brown butter into the bowl of an electric stand mixer. Make sure to scrape in all the dark particles...They add a lot of flavor! Add the brown sugar and beat the mixture on high until light and fluffy, about 5 minutes. It's okay if there are a few brown sugar chunks left.
Scrape the bowl and set the mixer of low. Beat in the eggs, vanilla extract, baking powder, and salt. Once well-combined, slowly add in the flour. Turn the mixer off when the mixture looks smooth.
Place the granulated sugar in a small bowl. Use a 1 1/2-tablespoon cookie scoop to portion out the cookie dough. Roll the scoops into balls, then roll each ball in the granulated sugar to coat.
Place the cookies two inches apart on the baking sheets. Use the bottom of a drinking glass to press to dough balls into flat 1/2-inch disks.
Bake for 8-10 minutes. The cookies should look golden around the edges, but a little under-baked in the center. Cool on the baking sheets.
Light or dark? The cookies in the photos were made with light brown sugar. However, we've made them with dark brown sugar for an even richer flavor. Your call!Keep in an air-tight container at room temperature for up to 2 weeks.