Sieve the flour into a bowl and make a well in the middle. Combine the crumbled yeast, 2 teaspoons of sugar, 1/4 1 milk and some flour from the edge to a thick paste. Dust with flour, cover and let rise until cracks appear in the flour layer.
For the filling, mix nuts, sugar, apple, lemon juice, lemon zest and whipped cream.
Then preheat the oven to 200 ° C.
Halve the yeast dough, roll out both parts 4 mm thick, cut into 8 equal triangles. Put 2 teaspoons of filling on each part and roll up from the broad side into croissants. Bake in the middle of the oven for 20 to 25 minutes. Brush with icing sugar while still hot.