Remove any tough stalks from the spinach and wash the leaves in plenty of cold water. Pat dry with paper towels.

Roll out or press the potato base, using a rolling pin or your hands, into a large 25 cm (10 inch) circle on a lightly floured work surface. Place the round on a large greased baking sheet (cookie sheet) or pizza pan and push up the edge a little. Spread with the tomato sauce.

Arrange the spinach leaves on the sauce, followed by the tomato slices. Top with the remaining vegetables and the herbs.

Mix together the cheeses and sprinkle over. Place the artichoke heart in the centre. Drizzle the pizza with a little olive oil and season.

Bake in a preheated oven, 200°C/400°F/Gas Mark 6, for 18 - 20 minutes, or until the edges are crisp and golden brown. Serve immediately.