Turn your oven to 250C (480F). Line a 28cm (11 inch) springform pan with baking paper. I just tear an extra wide sheet and dampen it with water from the tap. Then scrunch and smooth it to line the base and sides of the pan. OR line a baking tray with paper.
Mix eggs, salt and almond meal in a bowl. Add water gradually until you have a thick batter (you may not need all the water). Tip the egg mixture into the lined springform and use a spoon to spread it to the edges OR if using the baking tray just spread it out into a circle approx 30cm (12 inches).
Swirl the tomato passata on top of the egg mixture. Top with torn prosciutto and sliced cheese.
Bake for 15 minutes for the spring form pan OR 10 minutes if using the baking tray or until the pizza is browned and feels springy when touched.