For the dough, combine flour, yeast and sugar in a bowl. Stir in salt. Make a well in centre. Add water and oil. Stir to combine. Use your hands to bring dough together. Turn out onto a lightly floured surface. Knead for 10 minutes or until smooth and elastic. Brush a bowl with oil. Add dough. Turn to coat. Cover with a damp tea towel. Set aside in a warm place for 40 minutes or until doubled in size.
Meanwhile, heat a large frying pan over medium heat. Add half the spinach with the water clinging and cook, stirring, for 1-2 minutes or until wilted. Transfer to a bowl and set aside to cool slightly. Repeat with the remaining spinach.
When spinach is cool enough to handle, squeeze out excess water. Coarsely chop and place in a large bowl. Add ricotta, mozzarella, parmesan, shallot and lemon rind. Mix until well combined. Season.
Preheat oven to 200C/180C fan forced. Grease 2 large baking trays with olive oil and dust with extra flour.
Punch down the dough with your fist. Knead for 30 seconds or until dough returns to its original size. Divide into 6 equal portions and cover with plastic wrap. Roll out 1 portion of dough on a lightly floured surface to a 20cm disc. Place one-sixth of the filling over half the dough, leaving a 2cm border. Lightly brush the border with water. Fold in half to enclose filling. Pinch edges together to seal. Place on a prepared tray. Repeat with remaining dough and filling. Brush each calzone with extra oil. Bake, swapping trays halfway through cooking, for 25-30 minutes or until golden.
Place the tomato and bocconcini in a microwave-safe bowl. Season well. Microwave on High for 4 minutes or until the cheese starts to soften. Stir in the basil.
Sprinkle the calzone with salt and dried chilli flakes. Serve with the caprese sauce and extra basil leaves.