Drain mozzarella on a paper towel then thinly slice into half moons.
Heat oven to 375ºF. Lightly toast bread on 2 baking sheets in the upper and lower third of the oven.
Heat a skillet or medium-size pot over medium-high heat. Add EVOO, 2 turns of the pan, and meat. Brown and crumble the meat then add onions and garlic, season with salt and pepper. Stir in tomato paste, passata or purée, milk, thyme and oregano. Simmer 20 minutes.
In a small bowl, combine parsley, ricotta, Parm, egg yolk, salt and pepper. Spread an even layer of ricotta over the 4 pieces of bread, top with sauce then a layer of fresh mozzarella. Bake pizzas until brown and bubbly on top, 17-18 minutes, garnish with torn basil and serve with a green salad alongside.