Whisk flour and baking powder. Make a well in the center and add eggs, sugar and salt. Cut the butter into pieces and spread evenly on the dough. Knead a smooth dough and refrigerate for 1 to 2 hours (it is best to wrap it in aluminum foil). Then roll out the dough (not too thin) and cut out cookies (here, of course, there are no limits to creativity). If you still have an old cast iron waffle iron from grandma, you can also form the dough into balls, press them in the waffle iron and then place them on a baking tray covered with parchment paper.
Baking time: in a hot-air oven for about 25 min. at 150 °C.