1. Preheat oven to 425°f. brush a rimmed baking sheet with oil.
2. On a lightly floured work surface, roll dough into a 16-inch round.
3. Spread ricotta on bottom half of dough, leaving a 1-inch border.
4. Top ricotta with spinach and mozzarella.
5. Fold top half over and roll and pinch edges to seal. brush off excess flour.
6. Carefully transfer calzone to baking sheet.
7. Lightly brush with oil, season with salt. bake until golden brown for 22 to 25 minutes.