Heat the oil in a pan and let the meat take on a light color. Add the mushrooms and let them collapse slightly, season with salt and pepper.
In the meantime, mix the creme fraiche, yoghurt, paprika paste, chilli and herbs and season with salt. Beat in the egg white well.
Put the meat and mushrooms in a tart dish. Spread the creme fraiche mixture on top. Cover the mold with puff pastry and press firmly on the outer edge of the mold. Cut 3-4 small holes in the dough. Whisk the egg yolks with a little milk and a pinch of salt. Brush the dough with it. Bake at 180 ° for about 20 minutes until the dough is golden brown. Serve immediately.