• Preheat oven to 450°.
• On a lightly floured surface, roll dough to ⅛-inch thickness. Using a 4½-inch round cutter, cut circles from pie dough. Press each dough round into a 4-inch tart pan. Prick bottoms with a fork. Place tart pans on a baking sheet.
• Bake until golden brown, 7 to 8 minutes. Cool on wire racks for 5 minutes. Remove tart shells from pans, and let cool completely.
• In a large bowl, whisk together the ricotta and eggs until smooth. Add the prosciutto, basil, oregano, salt, and pepper.
• Reduce oven temperature to 350°.
• Line 2 baking sheets with parchment paper.
• Place prepared crusts on the prepared baking sheets. Divide the ricotta mixture evenly among prepared crusts. Sprinkle each tart evenly with Parmesan, and place 3 to 4 slices tomato on top. Using fingertips, gently press tomato slices into the filling.
• Bake until golden brown, 25 minutes. Cool on pans for 5 minutes. Transfer to wire racks to cool completely.
• Garnish with fresh basil, if desired. Serve at room temperature.
NOTE: Tarts can be made up to 2 days in advance. Keep in an airtight container in the refrigerator. Reheat before serving.