Rinse and peel the apples. Remove the core and cut the apples in smaller pieces.
In a sauce pan; add water, the apple pieces, sugar and the seeds from a vanilla bean. Also add the empty vanilla bean, it still have a lot of flavor.
Heat up the apple mixture and let it simmer until the apples are tender. If the apples are sour you should add a little extra sugar. When the apples are done; set aside to cool off completely.
Pour the hazelnuts in an oven proof dish and bake them for 10 minutes at 200 C (400 F).
Pour the warm hazelnuts in a clean dishcloth and rub them well until most of the skin are removed.
Pour the sugar on a frying pan and slowly melt it at medium heat. Do not stir in the sugar while it is melting. Let the sugar melt completely and become light brown.
Add the skinned hazelnuts to the molten sugar and stir in the mixture for about 1-2 minutes. Pour the hazelnut croccante on a sheet of parchment paper and let it cool off.
When the hazelnut croccante is cooled off; chop it using a food processor or similar.
Whip the heavy cream into a whipped cream.
Now the apple trifle are to be assembled; Use two large or four smaller glasses; Start with a layer of apple puree, then some hazelnut croccante and then some whipped cream. Continue until you have the amount of layers you like. We normally have two layers. Finish off with some of the hazelnut croccante. Serve right away or keep it refrigerated.