Cut the butter into cubes and melt it in a small saucepan, over a medium to high heat. Once melted, you want to keep heating it, stirring occasionally with a wooden spoon, until brown specks appear and you can feel that nutty aroma. Be careful not to burn the butter, but also don't "underbrown" it - if you know what I mean.
Once your butter is browned, transfer it to a bowl and let it cool to room temperature. You can do this in a fridge to speed up the process.
While your brown butter is cooling, sift together flour, baking soda and salt, and put aside. Chop the chocolate into chunks medium sized chunks, or a mix of small and big.
Once your butter has come to room temperature, add to it both of the sugars, an egg and vanilla extract. Combine together using a whisk.
Add the dry ingredients and chopped chocolate to wet ingredients and fold everything together using a silicone spatula or a wooden spoon.
Once your dough is ready, it's best to let it rest in the fridge overnight in order to enhance all the flavors. Before baking it, be sure to take it out of the fridge and let it come to room temperature.
If you don't like the idea of letting your cookie dough rest overnight, you can bake it right away - it'll still be delicious :) But let the dough sit in the fridge for at least 20-30 minutes, so the flour can have the time to absorb the moisture.
Preheat your fan oven to 160°C (325°F) or 175°C(350°F) if you’re not using a fan oven and line the baking sheet with baking paper.
Using an ice cream or a cookie scoop that has a 5-cm diameter, scoop out the cookie dough onto the prepared sheet by leaving a 3-inch (7-cm) gap between each. (Each cookie dough ball weighs between 70 to 80 grams)
For soft and chewy cookie with crispy edges - bake them for 10-12 minutes.
When they are done, they will be really soft at the touch (looking almost underbaked), but the edges will be slightly golden and crispy.Take out the baking sheet and give it a couple of bangs on the counter, to create the signature wrinkly chocolate chip look.**
Leave them for 2 minutes on a baking tray and then transfer them to a cooling rack.
Keep the baked cookies in an airtight container, at room temperature for 3-5 days.
Make sure to strain light muscovado sugar through a sieve to get rid of large chunks of it in the batter.
If you're not sure how hot your oven is, you can bake a "test cookie" to see what's the best time and temperature.
If you still don't own one, I advise you to buy a kitchen scale - they're cheap and easy to use, and always guarantee the same results in baking! :)
Letting the dough chill overnight in the fridge really did enhance all the flavours, but if you don't have time and you want your cookies ASAP, they will still be delicious baked right away.