Melt 30 g butter in a pot. Dust with flour and gradually stir in the milk. Simmer for 2-3 minutes. Set aside. Mash feta finely with a fork. Grate Greyezer and Pecorino finely.
Stir the cheese into the sauce. Season to taste with pepper and nutmeg. Melt 80 g butter in a saucepan. Lay the filo pastry apart. Wrap the dough in a damp tea towel. Lightly spread 6 tartlet cups (each 11 cm Ø) with butter.
Brush the dough sheets with the remaining butter and cut them into 12 cake pieces each. Place 2 pieces of dough on top of each other in 1 mould. Spread the cheese mixture on top. Place 2 pieces of dough on top of each other in opposite directions.
Cover the moulds with it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas. Level 3) for 12-15 minutes until golden brown. Serve garnished with mint and rosemary.