For the matcha pavlova:

1. Preheat oven to 400 degrees.
2. In a large bowl, beat the egg whites with a hand mixer on high, until the egg whites hold stiff peaks. Continue to beat the egg whites while slowly adding the sugar, a bit at a time, until the sugar is fully dissolved.
3. Mix in the lemon juice and vanilla extract. Once it is well-combined, sprinkle in the cornstarch and matcha and continue to beat until the mixture is glossy, about 5 more minutes.
4. Spoon the meringue mixture onto a parchment paper lined baking sheet. Reduce the oven temperature to 200 degrees. Immediately transfer the pavlova to the oven.
5. Bake the pavlova for 1 hour and 30 minutes. Turn off the oven and allow the pavlova to cool completely inside of the oven, letting it sit for at least 2 hours.
6. Store the pavlova in an airtight container until ready to decorate and serve. Try not to decorate more than a couple of hours in advance or the pavlova will soften.

For the vanilla bean mascarpone:

1. In a bowl of cold water, rehydrate gelatin sheets for 10 minutes.
2. Spread the vanilla pod with a knife, split it lengthways and scrape out the seeds. Add the vanilla beans to the mascarpone.
3. In a saucepan, heat the mascarpone and sugar until smooth and creamy. Add the gelatine and stir to dissolve. Remove the mascarpone mixture from the heat.
4. In a large bowl, whip the cream until stiff. Once the desired texture has been achieved, gently fold the whipped cream into the mascarpone using a blender.
5. When the mixture is smooth, leave to rest in the fridge for at least 3 hours.
6. Once the cream has cooled and set, stir it vigorously until it falls slightly: this will make it easier to use for piping onto pavlova.
7. Use a piping bag to pipe the cream onto the pavlova.