To make the pastry base, place the butter, flour, cornflour, baking powder, sugar, vanilla and 1/4 teaspoon salt in a food processor and process to combine until the mixture is crumbly. Press the dough into a 10 x 36cm greased and lined tart pan with a removable base. Refrigerate for 30 minutes to chill.
Preheat the oven to 180°C.
Meanwhile, place the butter, sugar, vanilla, almonds and milk in a saucepan over low heat, stirring, until butter has melted. Set aside to cool slightly.
Spread the marmalade over the pastry base, pour over the topping and bake for 25-30 minutes until golden and cooked through. Serve warm.
* You can substitute the marmalade with your favorite jam, if desired.