Preheat oven to 180° Celsius and line the bottom of a tart pan with baking paper. Place oats into a food processor and blend until it is a coarse meal. Transfer to a mixing bowl and use a wooden spoon to stir in the remaining ingredients.
Pour the mixture into the tart pan and use your fingers to press it firmly down to make a crust. Bake for 15 minutes, then set aside to cool.
Melt the chocolate chips in a double boiler (boil water in a small pot and melt chocolate in a heat safe glass or steel bowl on top of the boiling water).
Place the remaining filling ingredients and the melted chocolate into a food processor or blender and blend until creamy and no lumps are left. Once the crust is cooled to room temperature, pour the filling in and use a spatula to spread it evenly.
Refrigerate and allow it to set for at least 6 hours.