Prepare and bake your tart crust. If you are going to make our tart crust recipe, you can click on the "Tart dough" ingredient on the left and follow the instructions.
Preheat the oven to 175 °C / 350 °F. Clean and core the apples and slice them thinly. Arrange the apple slices in concentric circles over your baked pie crust and brush them with a mixture of melted butter, 1 teaspoon of caster sugar and 1 tablespoon of Calvados brandy / rum. Place in the oven and bake for 30 minutes at 175 °C / 350 °F.
Remove apple tart from the oven. In a large bowl combine sour cream, double cream, eggs and caster sugar. Pour the mixture over baked apples and place back in the oven. Bake for another 8 - 10 minut at 175 °C / 350 °F or until the filling is nice golden. Remove from the oven and let it cool slightly.
Beat together the yolk and the sugar, using a whisk. Beat until the mixture is smooth and pale. Add the milk to a saucepan. Slice the vanilla bean lengthwise and scrape the seeds into the milk. Bring the milk to a boil. Whisk the milk into the yolks mixture, then pour the mixture back to the saucepan. Place on the stove, over a low heat, stirring with a spatula and scraping the bottom of the saucepan to keep it from sticking, until the sauce thickens, be careful not to get scrambled eggs. Remove from the heat and let it cool slightly, serve with your apple tart.TipVanilla sauce should not reach more than 80 °C / 170 °F while cooking.