Knead the spelled flour and wheat flour with the brown sugar, the soft butter and the egg to form a dough. Scrape out the vanilla pod and knead in. Spread the dough in a tart pan with a diameter of 28 cm and press down. Form a small edge in the process. Prick the dough several times with a fork.
Peel the apples, remove the core and cut into fine slices, spread over the dough in a fan shape. Mix the crème fraîche and sour cream with the egg and brown sugar. Finally mix in the contents of the scraped out vanilla pod and spread the icing over the apples. Bake the tart in the oven at 180 ° C for about 45 minutes.
After baking, let cool on a rack and enjoy. If you like, you can also add a little lightly whipped cream.