1. Start by preparing some brown butter. Add the butter to a small saucepan and heat until it melts. Let the butter cook for a few minutes – it will bubble quite a bit. The bubbles will die down at some point and the butter will start to foam up, get dark speckles at the bottom of the saucepan, and smell nutty – this means the brown butter is done. Transfer immediately to a heatproof bowl (melted butter and the brown but not black speckles from the bottom). If you leave the butter in the saucepan, it will continue cooking and might get an unpleasant burnt flavor. Set aside to cool down.

2. Add the cooled brown butter and brown sugar to a large bowl and mix until light and fluffy. Next add the egg, egg yolk, and vanilla extract and mix until well combined. Add the spelt flour, baking soda, and salt and fold in until you can’t see dry spots anymore. Add the chopped chocolate (keep a small amount for decorations) and fold in. Place the dough in the fridge overnight.

3. Preheat the oven to 190°C (375°F). Line a baking sheet with baking parchment and set aside. Weigh out about 2 oz. (60g) pieces of dough and shape them into balls. Press some pieces of the reserved chocolate into the dough and place the balls with enough space in between on the baking sheet – I could fit five cookies on a baking sheet. Keep the rest of the dough in the fridge.

4. Bake the cookies for 12-14 minutes or until the edges are set and have gotten some color – the centers of the cookies should still be a bit soft. Take out of the oven and sprinkle the cookies with some flaky sea salt immediately, if you like. Let the cookies cool down a bit on the baking sheet, then transfer to a wire rack and let cool down completely. Prepare the next batch and bake more cookies until the dough is all used.