Spread tomato paste evenly over pizza base. Top with spinach leaves, sliced onion, chicken, capsicum strips and cherry tomatoes. Sprinkle with cheese and place on a baking tray, pizza stone or wire rack.
Bake for 5 minutes until cheese is melted then cover with foil to prevent burning. Bake for a further 5 minutes until base is crisp.
Sprinkle with roughly torn basil leaves on top to serve.