Drain the cherries well and collect the juice. Stir starch and 2 tablespoons cherry juice until smooth. Boil up the rest of the juice with 1 tbsp. sugar. Stir in starch and simmer for about 1 minute. Remove from heat. Let it cool down.
Melt the butter. Put the butter cookies in a freezer bag and crumble them finely with the dough roll. Mix with butter.
Place the appetizer ring (8 cm Ø) or a ring you have made yourself from aluminium foil on a tray lined with baking paper or on a board. Pour in 1-2 tbsp. cookie mixture and press until smooth. Remove the ring.
Make 5 more bases from the remaining mass. Chill for about 30 minutes.
Mix the quark with 2 tablespoons of sugar. Whip cream with cream stiffener until stiff. Crush the cherries a little bit with a fork and fold into the quark with the cream. Spread the cream loosely on the biscuit bases. Cover and chill for about 1 hour.
Sprinkle the tartlets with cherry sauce and serve.