Preheat the oven to 300 degrees.
In a medium bowl, combine the almond powder and powdered sugar.
In a small saucepan, combine the sugar and water and bring to 260 degrees fahrenheit (to create a syrup - it's finished when it comes to temp).
Meanwhile, in a separate bowl, whisk the 23 grams of egg whites until medium peaks form.
Pour the hot syrup over the beaten egg whites and continue to whisk until cool to the touch. The meringue should be thick and glossy.
Mix matcha powder into the bowl with the the almond powder and powdered sugar, then mix in the 21 grams of egg whites.
Add the meringue into the mix and carefully fold them together until the texture softens and becomes glossy.
Pipe the batter small rounds (2 cm) on to a lined baking sheet (a silpat ideally), and bake for 15 mins. (before baking, she slammed the baking sheet onto a table or cutting board, so any air bubbles would get released)
Let the shells completely cool before removing & filling.
Roll the Azuki bean paste into small balls and place them between the shells and assemble the macarons.