For the dough, mix flour with sugar and pile on a work surface. Form a well, add egg yolks and cold butter pieces in the well. With a large knife, chop ingredients until crumbs form. Knead all the ingredients quickly with both hands into a smooth dough. Form a ball, wrap in plastic wrap and set aside to cool for approximately one hour.
After the cooling time, roll out dough into a circle about 20 cm (approximately 8 inches) in diameter and place in a greased and floured tart pan. Tart pan should be 15 cm (approximately 6 inches) in diameter. Press dough edges firmly and let rest in a cool place again for 20 minutes.
For the filling, rinse rhubarb, trim and peel rhubarb. Slice rhubarb stalks in half and cut into 2 cm (approximately 1 inch) pieces.
Mix egg with egg yolk and sugar. Stir in quark. Spread filling mixture over the tart crust and top with the rhubarb pieces.
Bake in preheated oven 20-30 minutes until golden brown.
Remove from oven, sprinkle liberally with powdered sugar and let cool.