First make the crust. Preheat oven to 350F.
1) Thoroughly oil a fluted 9-inch tart pan with removable bottom and set aside.
2) Add oats, coconut, oat flour, cocoa powder and salt to a food processor and blend until oats and coconut are finely ground.
3) Place in a bowl and stir in almond meal and brown rice flour.
4) Stir in coconut oil and mix until all the flour is moistened.
5) Add maple syrup and vanilla and mix again until the dough forms a ball. If it’s not holding together, add a teaspoon of maple syrup. If dough is very sticky set it aside for 10 minutes to thicken up.
6) Wash and dry your hands and press crust thinly and evenly into prepared tart pan.
7) Prick with a fork and bake 18 minutes. Remove from oven and set aside to cool.
For the filling
1) Line a large strainer with a nut milk bag or several layers of cheesecloth. Place strainer over a medium pot and set aside.
2) Drain and rinse cashews, and add them to an upright blender.
3) Add coconut and 3 cups water, blend on highest speed until smooth.
4) Pour into lined strainer and gather the edges of the bag or cloth and gently squeeze out all liquid. Compost solids. You should have 3 cups of coconut-cashew milk, if not add a little water. Rinse out blender.
5) Add maple syrup and agar flakes to the pot and bring to a boil over medium-high heat, whisking constantly.
6) Reduce heat to low, cover pot and simmer for 15 minutes or until all agar flakes have dissolved. Whisk mixture every 5 minutes to prevent sticking.
7) Remove from heat, uncover pot and allow to cool for 10 minutes, then pour mixture into blender.
8) Add matcha and vanilla and blend until evenly combined and foaming.
9) Gently pour into tart crust. Allow to sit for another 15 minutes before transferring to the refrigerator to set. This takes about 1 hour or until it is completely chilled.
10) Use a small strainer to dust with matcha. Serve chilled.