Mortadella and Marinated Artichoke Tartines

Name: Mortadella and Marinated Artichoke Tartines
Ingredients: 1/2 cup ricotta; 3/4 ounce Parmigiano-Reggiano, finely grated (1/4 cup), plus more, shaved, for, serving (optional); 3 tablespoons extra-virgin olive oil, plus more for drizzling; Kosher salt and freshly ground pepper; 4 thick slices ciabatta (or 2 small ciabatta rolls, split in half) or similar rustic bread, lightly toasted; 4 ounces thinly sliced mortadella; 2 Italian-style marinated artichoke hearts (from 1 small jar), drained; Sliced arugula leaves, for serving