Melt the butter in a saucepan over medium heat. Stir and swirl occasionally until it foams, turns golden brown, and smells nutty. Scrape browned bits into a large mixing bowl and let it cool for 10 to 15 minutes.

Whisk brown sugar and granulated sugar into the brown butter until combined.

Incorporate the egg, egg yolk, and vanilla extract, whisking until the mixture is smooth and glossy.

Stir in the sourdough discard until well mixed.

In another bowl, whisk together the flour, baking soda, baking powder, salt, and cinnamon.

Combine the dry ingredients with the wet ingredients, stirring with a spatula or wooden spoon until just combined. Fold in the chocolate chips.

Cover and chill the dough for at least 2 hours or up to 72 hours.

Preheat the oven to 350°F and line baking sheets with parchment paper. Scoop dough into 2-tablespoon-sized balls and arrange them 2 inches apart.

Bake for 10 to 12 minutes or until the edges are golden and the centers appear slightly soft.

Press extra chocolate chips on top and use a glass to gently shape the cookies into perfect circles.

Let cool on the baking sheet for 5 minutes, then move to a wire rack. Sprinkle with flaky sea salt if desired.