Mix the starch with 100 ml of nectar until smooth. Bring 150 g blueberries, vanillin sugar, 25 g sugar and 100 ml nectar to the boil in a covered pot. Stir in the starch and let it simmer for about 1 minute while stirring.
Add 150 g frozen berries, stir in and set aside. Bring milk and 40 g sugar to the boil. Add semolina while stirring, bring to the boil once. Remove from the heat, cover and allow to swell for about 5 minutes.
Amarettini, except for a few for decoration, crumble roughly. Separate the egg. Beat the egg white with salt until stiff, pour in 25 g sugar. Whisk egg yolk and cream, mix with 2 tablespoons of semolina, fold into the remaining semolina.
Fold in the beaten egg white and amarettine crumbs. Layer the semolina with the compote in 4 glasses. Decorate with set aside amarettini and serve immediately.