Line the bottom of a 8" by 4" loaf pan with parchment paper.
In a bowl, whisk together the egg, oil, sugar, matcha, vanilla, and salt.
With a spatula, fold the flour into the egg mixture. Be careful not to overmix. Set aside.
Make cheesecake filling:
In a stand mixer bowl fitted with a paddle attachment, beat together cream cheese, sugar, vanilla and egg yolk until smooth and creamy on low speed.
Scoop the matcha brownie batter into the bottom of the loaf pan. Spread the layer evenly with a spatula. Set aside 2 tablespoons of batter for the top.
Add the cheesecake filling on top of the matcha brownie batter.
Scrape the remaining 2 tablespoon of matcha brownie batter over top of the cheesecake filling.
Run a knife through the batter to create a swirl through the cheesecake and brownie mixture.
Tap the loaf pan once or twice to release any trapped air bubbles.
Bake at 350°F/177°C for 25-28 mins, until set in the middle, or a toothpick inserted comes out clean. Remove from the oven and cool on a cooling rack.
Let completely cool before slicing into squares. Dust with additional matcha powder if you like.
Place into a container for up to 1 day at room temperature, or in the refrigerator for up to 3 days. The tops will be appear a little moist if covered, but this is OK. If you prefer, you can dust with matcha before serving.
Recipe can be doubled to fit into a 8" x 8" baking pan. Bake for 28-30 minutes, until set.