For the yeast dough melt 150 g butter. Add milk, remove from heat. Stir yeast with 75 g sugar until liquid. Knead 500 g flour, 1 pinch of salt, eggs, yeast and milk mixture in a bowl with the dough hooks of the mixer until smooth. Cover and leave to rise in a warm place for about 1 hour.
For the crumbles, roughly chop the nuts. Caramelize with 75 g sugar in a pan. Let it cool down on baking paper. Melt 100 g butter. Mix with oat flakes, 60 g flour and 1 tbsp. sugar to form crumbles. Coarsely chop the brittle and mix into the crumbles.
Knead the dough again. With floured hands spread on the greased fat pan (approx. 32 x 39 cm). Cover and leave to rise in a warm place for about 15 minutes. Spread 150 g butter in pieces and crumbles on the dough. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer) for approx. 30 minutes. Let it cool down.