Line a large baking tray with parchment paper. Use a plate or a cake tin base to trace a 8-9" circle on the paper. Flip it over so the ink doesn't leak in to your meringue.
Whisk the egg whites in a bowl with a hand mixer or in a stand mixer for roughly 3 minutes, until they are white and fluffy.
Add the sugar gradually, roughly a few spoonfuls at a time, beating in between.
Mix until it is white, glossy and forms very stiff peaks. Rub a little between your fingers, if you can feel the grit of the sugar, beat for another minute.
Add in the vanilla, cream of tartar and corn flour and beat again.
Spoon out in to the centre of your circle and use a spoon or spatula to carefully spread out in to a tall disc with a slight depression in the centre.
Use a knife or a spatula to decorate the edges, if desired. I use a diagonal swipe upwards with a knife all the way around the edge.
Place in the oven and bake for 10 minutes, then reduce the temperature to 90c/200f and bake for another 90 minutes.
Switch off the oven and allow to cool for 20 minutes in the oven, then open the oven door and cool for another 10 before removing from the oven to cool completely on the side. This helps prevent cracking.
Once cool, lightly whip the cream and carefully spread on the top. Decorate with berries and serve immediately.
Best eaten immediately. You can prepare the base in advance and carefully wrap it in clingfilm to store it, then add the toppings and serve. If you have leftovers, store in the fridge and eat the next day but it really is best fresh!