Mix yogurt, sour cream, a dash of liqueur and the vanilla sugar into a cream. In the meantime, peel and dice the apples and heat butter in a pan. Add the apples and sauté. Sprinkle with cinnamon, caramelize with honey and deglaze with liqueur.
One layer each of apple pieces, cream and biscuits / ladyfingers in glasses layers. Finish the last layer with apples and garnish with cinnamon before serving.