Heat buttermilk until it reaches 100–110°F. Stir in the active dry yeast and a teaspoon of sugar, then let it sit for 10 minutes until frothy.

In a stand mixer, combine the yeast mixture with butter, sugar, egg, salt, and matcha-flour mixture. Mix on low, then knead for about 5 minutes until smooth and elastic.

Transfer the dough to a greased bowl, cover, and let rise for 1-2 hours until doubled in size.

Roll the dough into a square, spread butter, sprinkle with sugar and cinnamon, and roll into a log. Slice into 9 pieces and arrange in a greased pan.

Cover and let the rolls rise for another 1-2 hours until puffy.

Preheat oven to 350°F and bake for 20-25 minutes until golden brown.

Make the frosting by mixing cream cheese and butter until smooth, then add sugar, salt, vanilla, and matcha until well blended.

Cool the rolls for 10 minutes before frosting them with the matcha cream cheese frosting.