Bake for 12-15 minutes. Until puffed, and lightly golden.
About 30 minutes before you start to make your buttercream, remove butter from the fridge. Cut it into thin slices, about 1/4 inch thick. Set aside and let it come to room temperature. Depending on the temperature of your kitchen, you might need an hour or so to have the butter soften. Please note that you don’t want your butter to be too hot and melted either.