Let the dough rest for about 10 minutes at room temperature. Mash the feta with a fork. Grate the rest of the cheese. Melt 30 g butter in a pot. Dust with flour and sauté briefly until golden brown. Add milk while stirring and simmer for about 5 minutes.
Stir the whole cheese into the sauce and melt. Season to taste with pepper and nutmeg.
Melt 80 g butter. Spread 6 tartlet moulds with removable base (approx. 10 cm Ø each) thinly with butter.
Dough sheets apart and cut into 3 strips. Spread each strip thinly with some butter. Place 2 strips overlapping in the moulds, pressing them to the edge. Spread the cheese mixture on top and place another 1 strip on top so that the cheese mixture is covered.
Spread with rest of butter.
Bake in the preheated oven (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) for 12-15 minutes until golden brown. Garnish with mint and rosemary.