To Make the Pavlovas: Preheat oven to 225F. Line 1-2 large baking pans with parchment paper.
In the bowl of a stand mixer fitted with the whisk attachment, combine the cold egg whites, cream of tartar, and sugar. Beat on LOW for 2 minutes, then increase speed to beat for 5-6 minutes, or until stiff peaks.
Transfer the mixture to a piping bag with a large tip. Work in batches, if needed. You can also use a spoon.
Pipe 10-12 mounds onto the prepared baking pans.
Bake for 45 minutes, then turn the oven OFF without opening the oven door. Keep the pavlovas in the oven for an additional 1 hour.
To Make the Kiwi Custard: Combine the very finely chopped kiwi, egg yolks, egg, sugar, and lemon juice in a saucepan. Whisk until very well combined.
Place over medium heat. Continue stirring until the mixture has thickened, about 10-15 minutes.
Remove from heat to stir in the butter. Stir in the vanilla once the butter has melted.
Cover the surface with plastic wrap and store in the fridge to completely cool.
To Make the Matcha Whipped Cream: In the bowl of a stand mixer fitted with the whisk attachment, combine the heavy whipping cream, vanilla, powdered sugar, and 2 tablespoons matcha powder. Whisk on LOW speed for 2-3 minutes, until thickened a little bit, then increase to Medium speed to beat until soft peaks. Add more matcha to desired taste.
To Assemble: Add a generous spoonful of the kiwi custard into the centers of each pavlova, then pipe the matcha whipped cream on top, followed by another dollop of the kiwi custard. Garnish with edible flowers and thinly sliced Zespri SunGold Kiwi to enjoy within the hour!