1. Preheat the oven to 325. Butter or spray a 9 by 5 inch loaf pan and line with parchment paper, leaving an overhang.
2. Sift together the flour, baking powder, baking soda, cinnamon, nutmeg and cloves into a mixing bowl. Whisk in the ground houjicha and set aside.
3. In another mixing bowl (or the bowl of your stand mixer) beat together the squash puree, oil, both sugars and salt until well combined. Add the eggs one at a time, mixing after each addition. Scrape down the sides of the bowl. On low speed add the flour mixture. Continue beating for a few more seconds to make a smooth batter.
4. Transfer the batter to the prepared loaf pan and smooth out the top. Bake for 60-75 minutes or until a cake tester inserted in the center comes out clean. Let cool in the pan for 20 minutes, then invert it onto a cooling rack to cool completely.

Make the frosting

1. In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese, powdered sugar and vanilla on medium-high speed until soft and creamy, about 2-3 minutes.
2. Add the butter and continue beating until light and airy, 2 more minutes. Add the mascarpone and beat until fluffy. Frost the loaf, and lightly dust with matcha powder.