Slice bread in half so you have two round or long bases. Drain the peppers, reserving the oil. Spread 1 tbsp of the pesto over the cut side of each base.
Scatter over the peppers and watercress and crumble over the goat’s cheese. Mix the remaining tablespoon of pesto with a tablespoon of oil from the peppers and drizzle it over the pizzas. Scatter the olives over. Cut each pizza into wedges or slices and serve.