Preheat the oven at 250°C, with extra heat on the top and bottom oven elements.
In a bowl, add 3 whole eggs and only the whites from the other 3. Add 1 tbsp mascarpone, stirring, salt and a little pepper. Lay the fresh pizza curst in a small baking pan, pour the baby spinach on top and salt. Add the anthotiro cheese and eggs mix, evenly. Add the mozzarella. Cut 1 tomato in wedges and add them in the baking pan. Bake for approx. 10 min. Take the pizza out of the oven, smear with the 3 egg yolks that you have kept aside and bake for another 3-5 min.