Debark the toast. Cut the mozzarella into slices. Wash the basil, shake dry and finely chop. Pour the milk into a deep plate. Whisk the eggs in a deep plate, season with salt, pepper and oregano and stir in the basil.
Fill 2 slices of toast with mozzarella which is seasoned with pepper and 2 slices of Parma ham each.
Squeeze the filled toasts tightly and turn them in the milk. Dust all over with a little oil and place on the plate with the whisked eggs, leave to steep for 15 minutes, turn once halfway through.
Melt some butter in a pan and bake the toasts on both sides over medium heat until golden brown.
Place 2 filled toasts per person on plates and garnish with basil leaves.