Chill a medium stainless steel or glass bowl and whisk in the fridge for at least 30 minutes prior to whipping the cream.
Remove the chilled bowl and whisk from the fridge. Add the cold heavy cream and beat until foamy. Add in the powdered sugar and keep beating until almost stiff peaks. Add in the matcha and coconut extract and whisk until stiff peaks form.
Transfer the whipped cream into a piping bag fitted with a star tip.
Carefully cut the Coconut Cream buns lengthwise (and if you wish, remove some of the bread inside since it may be too bulky) and pipe in the matcha coconut cream.
Best served on the same day as made.
Can be refrigerated if not consumed right away, although the bread may stiffen a little while cold. A better way would be to only pipe the cream on prior to serving.