Preheat the oven to 325F and line a 9x9inch baking pan with foil

In a large bowl, beat together the butter and sugar

Then beat in the flour, matcha powder, and salt

Pour the shortbread dough into the lined baking pan and bake for 30-35 minutes or until the top is just a pale golden brown

Remove from the oven and allow to cool in the pan

Pour the condensed milk, butter, corn syrup, miso, and dark brown sugar in a medium saucepot and stir to slightly combine

Heat over low-medium heat until all the ingredients have melted together

Then turn the heat to medium high and heat until boiling (make sure to constantly stir the caramel as it heats up to avoid any of it sticking to the bottom of the pot and burning!)

Keep stirring the caramel as it boils, until it turns a light caramel color and is thick (220F)

Remove from heat and stir for a couple more minutes so that none of the caramel sticks to the bottom

Then pour the caramel over the shortbread base and chill in the fridge for 1-1.5 hours

Pour the dark chocolate chips in a microwave safe bowl and microwave at 30 seconds intervals until all the chocolate is melted

Repeat with the white chocolate

Remove the set caramel and shortbread from the fridge

Pour the dark chocolate on the caramel and smooth it out

Then pour the white chocolate over the dark chocolate, in 4 parallel lines across the top

Take a toothpick and lightly draw across the top to create a swirl effect

Put back in the fridge for another hour or until the chocolate is set

Then remove and cut the shortbread into 16 equal pieces and enjoy!