Melt the butter in a pan over medium heat until it turns golden brown and gives a nutty aroma. Let it cool slightly.
In a bowl, mix browned butter with brown sugar and granulated sugar until smooth.
Add the egg and mix well.
Stir in oats and flour to form a dough.
Fold in the chocolate chips.
Scoop small portions onto a lined baking tray.
Bake in a preheated oven at 180°C (350°F) for 10–12 minutes until edges are golden.
Let the cookies cool before serving.