Preheat the oven: preheat the oven to 180°C / 350-375°F / Gas Mark 4-5.
Tomato mixture: add sliced cherry tomatoes, chopped onion and basil pesto to medium sized mixing bowl and use a spoon to stir and combine. Then set aside.
Pizza base: lay pizza base on a silicon baking mat on a flat baking tray, sprinkle with grated mozzarella cheese.
Melt cheese: place cheese topped pizza base into the oven (middle shelf) and cook for 2 mins till the cheese melts. Use oven mits to remove from oven and place on a heat proof surface.
Tomato layer: use a soup spoon to dollop the combined tomato pesto mixture over the top of the melted cheese. Flip the spoon to the back and use it to spread out into a thick layer.
Bocconcini balls: place the bocconcini balls on top of the tomato pesto mixture, spread across the pizza base.
Oven bake: place the topped pizza base into the oven and cook for 25 to 30 mins till the base is crispy and the bocconcini has melted. Use oven mits to remove the cooked pizza from the oven and place on a heatproof surface. Rest for 1 to 2 mins.
Basil and balsamic: sprinkle the freshly chopped basil leaves over the top of the cooked pizza. Drizzle the balsamic glaze over the pizza back and forth in a zig zag manner.
Serve and enjoy: use a pizza wheel to slice the pizza into pieces. Serve immediately.