Into a blender, start by adding the eggs, the milk, the olive oil or oil, the grated parmesan and the salt, mix it all very well until combined.
With the blender still on, open the lid and add the wheat flour gradually, blend it all again and add the baking powder. Gently mix it.
Now, into a ring cake mold greased with butter and flour, pour 1/3 of the batter, spread it very well on the bottom.
Add 150g of the sausage chopped into thin round slices, add 100g of the mozzarella cheese and the tomato cut into thin slices.
Add another 1/3 of batter, another 150g of sausage, a thinly sliced tomato and another 100g of mozzarella cheese.
Top it with the rest of the batter, spread very well and add another 50g of mozzarella.
Bake in a preheated oven at 180°C (356°F) for 35 minutes. Baking time may vary depending on the power of your oven.
Serve.