Combine the sugar and butter together in a bowl and melt them well in a microwave. (You can do this over a stove too.)
Combine the flour, butter mixture and egg yolk and mix well.
Scoop out the cookie mixture with a large spoon and place it onto an oven tray. Set the time for 10 minutes at 160 C. When the cookies are baked, take them out and cool down on a wire rack. Serve.