In a light-colored pan over medium heat, melt the butter and keep stirring with a rubber spatula as it cooks. Watch for it to foam, turn a lovely golden brown, and smell nutty and rich. This should take about 6 to 10 minutes. You’ll see little brown bits forming at the bottom – that’s where all the flavor is!

Pour the browned butter and those tasty milk solids straight into a heatproof measuring cup. You should end up with about 185 to 195 grams (around the ¾ to 1-cup mark). If you’ve lost a bit too much liquid, just stir in 1 to 4 teaspoons of water until you reach the right amount.

Let the butter cool to room temperature, about 30 to 40 minutes on the counter or 20 to 25 minutes in the fridge. It should still be pourable when you’re ready to use it.

In a large bowl, whisk together the cooled brown butter, brown sugar, and granulated sugar until the mixture looks smooth and glossy. This should take about 1 to 2 minutes.

Add the eggs, egg yolk, and vanilla, then whisk again until the batter turns light and creamy, about 1 minute.

In a medium bowl, combine half of the flour (120 g) with the baking soda and salt. Gently fold this into the wet ingredients using a spatula until everything comes together.

Add the remaining flour a little at a time, stopping if the dough starts to feel too dry.

Fold in the mini chocolate chips, semisweet chocolate chips, and chopped dark chocolate just until everything is evenly mixed. Try not to overwork the dough.

Scoop out the dough using a 2-tablespoon cookie scoop and form it into balls. Press a few extra chocolate chips on top if you’d like picture-perfect cookies.

Place the dough balls on a parchment-lined baking sheet, cover them, and chill in the fridge for at least 4 hours or overnight. This helps them bake up thick and chewy.

Preheat your oven to 350°F (175°C). Line 2 to 3 baking sheets with parchment paper and arrange the chilled dough balls about 2 inches apart.

Bake for 8 to 11 minutes, just until the edges are golden and the centers look slightly puffed.

Let the cookies cool on the baking sheet for 5 minutes, then move them to a wire rack to finish cooling completely.