Quark Ice Cream with Toasted Cereal
Rinse lemon with hot water, wipe dry and finely grate zest. Squeeze juice from lemon. In a bowl, whisk together quark with half the sugar, vanilla sugar, lemon juice and zest until smooth.
Heat cream and milk in a saucepan. Whisk together yolks with remaining sugar in a bowl. Place bowl over a pan of simmering water. Stirring constantly, whisk warm cream and milk mixture into yolks until creamy. Then place bowl over a bowl of ice water and whisk until mixture is chilled, about 10 minutes. Whisk in quark mixture. Cover and refrigerate about 30 minutes.
Transfer mixture to an ice cream maker and freeze according to manufacturer's directions, about 30 minutes.
Meanwhile, toast cereal flakes briefly in a dry pan. Sprinkle cereal with brown sugar and continue cooking until caramelized. Spread on a piece of aluminum foil to cool.
Scoop ice cream into small bowls and garnish with caramelized cereal flakes.