1. Heat oven to 500 degrees . Grease a 17 x 12-inch rimmed baking sheet with olive oil. Drop pizza dough into center of greased sheet, and use fingers to press out and flatten dough so it spreads as close as possible to corners of pan. This may seem difficult but persist, as a thin crust will be worth it.
2. Scatter mozzarella slices over dough and brush exposed edge of crust with olive oil. Bake for 15 minutes, until crust is crispy and cheese bubbly. (If cheese starts to get too brown, cover center of pizza with foil.)
3. While pizza bakes, toss together arugula, Parmesan, 3 tbsp of the oil, the lemon juice, salt and pepper. When pizza is ready, let cool for about 2 minutes and top with salad. Top with 12 spoonfuls of ricotta (1 tbsp each). Cut into squares and serve.