Preheat the oven to 220°C (Gas Mark 7) and place a pizza stone or baking tray inside.
Place the 30cm ready-made pizza base on the hot pizza stone or baking tray.
Spoon the pizza sauce evenly over the base, leaving a 1cm border around the edge.
Scatter the shredded mozzarella over the sauce.
Arrange the sliced pepperoni over the cheese.
Scatter the sliced mushrooms over the pepperoni.
Bake for 12–15 minutes, until the base is golden and the cheese is bubbling and lightly browned.
Remove the pizza from the oven and leave to rest for 5 minutes before slicing and serving.