Here is how you do it
Base: Mix all ingredients in a food processor until a dough is formed. Press the dough into a tart pan and allow it to chill for 20 minutes. Bake the base at gas mark 6 (200 °C) for approx. 10 minutes.
Filling: Press the lemons. Put the lemon juice, butter, sugar, eggs, and lemon zest in a saucepan and set on a low heat. Whisk continuously until the mixture begins to thicken, and then add Snøfrisk®. Pour the filling in the tart shell and bake at gas mark 1 (120 °C) for 10 minutes. Cool before serving.