1 Mix the salt and flour. Cream the yeast with the sugar, add the lukewarm water and mix with the flour. Knead to an elastic dough (adding more lukewarm water if required). Cover and put to rise in a warm place out of draughts for about 60 minutes.
2 Wash the courgettes and slice thinly lengthwise using a potato peeler. Clean the mushrooms and cut into wafer-thin slices. Preheat the oven to 240°C (220° fan) | 475F | gas 9.
3 Knead the dough again and divide into four equal pieces. Form into balls and roll out into circles (not too big). Leave to rise (prove) for a further 30 minutes.
4 Line two baking trays with baking parchment and place 2 pizza bases on each tray. Brush each pizza with 3 tbsp olive oil (leaving the edge free) and sprinkle with salt and pepper. Add 2-3 small pieces of rosemary. Top with the courgette slices, mushrooms and olives. Grate a little Parmesan over each pizza.
5 Put into the oven and bake for about 20 minutes, until golden brown.