You won't miss the crust with this high-protein "pizza."
Heat a large cast-iron skillet or griddle over medium-high, and preheat the broiler.
Working with 1 breast at a time, butterfly the chicken by cutting horizontally with a sharp knife almost all the way through. Open like a book and pound between sheets of plastic to about 1/4 inch thick. Season the chicken with salt and pepper. Add 1 tbsp. oil, one turn of the pan, to the cast-iron skillet. Add 2 chicken breasts and cook until golden and cooked through, 2 to 3 minutes per side; transfer to a foil-lined baking sheet. Repeat with 1 more tbsp. oil, one turn of the pan, and the remaining 2 chicken breasts.
In a medium bowl, mix the ricotta, parsley, grated Parm, garlic and a drizzle of EVOO; season with salt. Spread the ricotta mixture thinly over the chicken and top with the mozzarella. Broil until browned and bubbly, about 5 minutes.
In a large bowl, toss the spinach and arugula with the shaved Parm curls, lemon juice and a drizzle of EVOO; season with salt.
Top pizzettes with a small mound of spinach and arugula salad.