Preheat oven to 180 celsius. Grease a rectangle tart tin. Set aside.
In a food processor, combine oat flour, almond meal, pinch of cocoa powder and salt. Then add the coconut oil, and maple syrup and pulse to combined. You should get a moist mixture than can be easily moulded. Firmly press into bottom and up the sides of tart tin. Bake for 15 minutes until crust is golden brown. Transfer to a wire rack and let it cool while you're preparing the filling.
In a saucepan, whisk together cream, milk, matcha, vanilla and sweetener. Bring to the boil then whisk in agar agar and corn flour. Let it simmer for 2-3 minutes until agar is dissolved. Whisking constantly. Remove from heat and strain it through a fine mesh sieve into a heatproof bowl. Allow mixture to cool for 5 minutes.
Pour the mixture into cooled tart. Let sit in the fridge to set, about 4 hours. Garnish tart as desired with fruits and enjoy!