The extra step of browning the butter adds a toasty, nutty depth that elevates these from good to obsession-worthy.
Brown the butter: melt in a light-colored saucepan over medium heat, swirling constantly. It will foam, then the foam subsides, and golden-brown milk solids appear at the bottom. Smells like hazelnuts. Remove from heat immediately and pour into a large bowl, scraping every bit of the brown bits.
Whisk both sugars into the warm brown butter vigorously for 2 minutes until combined.
Add eggs and yolk one at a time, whisking after each. Add vanilla. The mixture should look thick and ribbon-like.
Fold in flour, baking soda, and salt until just combined. A few streaks of flour are fine.
Fold in chocolate chips. The dough will be very soft.
Chill the dough for at least 30 minutes (or up to 72 hours — longer = better flavor).
Preheat oven to 180C / 350F. Line baking sheets with parchment.
Scoop dough into 50g balls (about 2 tablespoons). Bake 11-13 minutes until edges are set but centers still look underdone. They firm up as they cool.
Immediately sprinkle with flaky sea salt. Cool on pan for 5 minutes before transferring.
Add 200g dark chocolate chips. Swirl 2 tbsp cocoa in the batter before the final fold. The brown butter keeps it from being cloying.
Four overripe bananas and brown butter. The loaf that actually improves every day for three days. Tested 14 times to get the crumb right.
Coconut oil toasted until fragrant substitutes for brown butter almost perfectly. Flax eggs do the work. Tested 4 times.
Replace 30g butter with tahini. Swirl more tahini and honey on top before baking. Sesame and banana is an underrated combination.