Dissolve the yeast in the lukewarm water. Mix the flour with the salt, pour in the yeasty water and knead for 8-10 minutes into a smooth, elastic dough.
Shape into a ball, cover and chill for 30-60 minutes.
Flatten the butter between two sheets of baking paper into a square of about 15×15 cm and keep it in the fridge.
Roll the dough into a square about 1 cm thick and 22×22 cm, put the butter slab in the middle and fold the four corners of the dough over it so it's completely covered.
Roll into a long rectangle, then fold in three like a letter. Chill for 20-30 minutes. Repeat once more.
Before the third rolling, sprinkle the worktop and dough generously with most of the sugar, and roll and fold it in three like that — the sugar goes between the layers. Work quickly, as the sugar draws moisture and starts to stick.
Butter a 20-22 cm round tin generously and sprinkle it with sugar. Roll the dough into a circle of about 25 cm and lay it in the tin, tucking the edges underneath.
Score the top in a diamond pattern with a sharp knife, brush with milk, sprinkle with sugar and leave to rise covered for 45-60 minutes.
Bake in an oven preheated to 180 °C for 35-45 minutes until deep amber and caramelised at the edges. Put a tray underneath, as the butter may bubble over.
Cool in the tin for 15-20 minutes (in that time the caramel sets but doesn't yet stick to the tin), then turn out and serve lukewarm, cut into wedges.
A Receptnaptár original recipe. Calories and protein are estimated.