1. Mix the flour and hazelnuts in a blender. Add salt, very cold butter, and a little ice water (if necessary). Mix until the dough comes together. Form into a ball and refrigerate.

2. Remove the earthy part of the mushrooms and Paris mushrooms; clean without passing under water with a brush; cut the mushrooms into slices.

3. Finely chop the clove of garlic.

4. In a pan, heat the extra virgin olive oil and sear the mushrooms. Add the garlic and cover. Cook over low heat until they release all their water. Drain.

5. Preheat the oven to 180°C.

6. Roll out the dough; butter 4 tartlet molds and line with the dough.

7. Grate the cheese. Beat the egg yolks with the sour cream. Season with salt and pepper, and add the mushrooms and cheese.

8. Fill the tartlet bottoms with the egg mixture; place on the lower rack of the oven.

9. Bake for 30 minutes or until golden brown.

10. Unmold and serve hot.