Preheat oven to 350F/180C. Line a 8x8 (20x20cm) baking pan with parchment paper.
In a small mixing bowl add oat flour, almond flour, sea salt, maple syrup and melted coconut oil. Mix to combine.
Transfer the base to the baking pan and flatten with a back of a spoon, or with your hand. Bake in the oven until golden, 8-10 minutes.
While your base is baking make the lemon filling. In a medium saucepan whisk together the lemon juice, date powder, agar agar powder and coconut cream. Cook the mixture on medium heat stirring often, until smooth and thickened into a custard consistency, 10 minutes.
Transfer the lemon filling to the baking pan and bake until the edges are slightly brown, about 15 minutes.
Let cool for 30 minutes, then put it in the fridge to chill for at least two hours, but preferably overnight.
Lift it out of the pan and cut into squares with a clean, sharp knife.