Mix yeast, flour, sugar and salt. Add 250 ml lukewarm water and knead to a smooth dough with the dough hooks of the hand mixer. Cover and leave to rise in a warm place for about 1 hour.
For the sauce, wash the basil, shake dry, pluck the leaves from the stalks and, except for a few leaves for garnishing, chop finely. Peel and chop the onion and garlic. Heat 2 tablespoons of oil, sauté onion and garlic for about 4 minutes while stirring.
Add tomatoes, bring to the boil and simmer for about 10 minutes. Chop the tomatoes with a spatula, add basil, season to taste with salt and pepper.
Clean the mushrooms and halve or quarter them depending on size. Heat 4 tablespoons of oil in a pan and fry the mushrooms for about 5 minutes, turning them over. Season to taste with salt and pepper.
Knead the yeast dough again and cut in half. Roll out the dough halves on a floured work surface (approx. 25 cm Ø). Spread sauce on the dough circles, spread ham and mushrooms on top.
Brush the edges of the dough with water. Fold the dough circles half over each, press the edges together. Place the two prepared Calzone pizzas on a baking tray lined with baking paper, sprinkle with cheese and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see
manufacturer) bake for about 25 minutes. Remove from the oven, arrange and garnish with basil.