Chocolate brownie with almonds & hazelnuts

1. Measure all the ingredients in separate bowls and sieve the flour
Cut the vanilla bean in half (lengthwise) and scrape the marrow out
In a pot, melt the butter on low heat and add the marrow of the vanilla to the butter
When the butter is fully melted, add the chocolate and sugar
Take the pot of the stove and whisk the mass until it is smooth and all the chocolate is melted
Let the mass cool down a little bit
Add flour and whisk it gently without creating lumps
While whisking add one by one the eggs and at last the crushed nuts
Place baking paper in a baking tray from about 30 by 30 cm
Pour the brownie mix in the tray
Bake the brownie for about 25 minutes on 160 celsius