Special equipment: 9-inch tart pan
Preheat the oven to 350 degrees F.
For the crust: Combine the butter, flour, and salt in a food processor. Pulse until the mixture looks like Parmesan cheese. Drizzle in half the cold water and pulse until the mixture forms a rough ball, adding the remaining water if needed. Remove the dough from the food processor, form into a disk, wrap in plastic, and refrigerate for at least 1 hour.
For the filling: In a small saucepan, melt the butter and cook it until it starts to brown and begins to smell like hazelnuts. Transfer the butter to the bowl of a stand mixer equipped with a paddle. Add the sugar and beat together on medium speed. Gradually add the flour. Once the flour has combined, add the eggs one at a time. Beat in the vanilla bean seeds.
For the apples: In a large saute pan, melt the butter over medium heat. Add the apples and sugar and cook until the apples start to soften, 6 to7 minutes. Pull the pan off the burner and add in the brandy. Return to the fire and flambe, if desired, or just let the alcohol burn off. Toss in the raisins.
To assemble: Remove the dough from the fridge 15 minutes before ready to use, this will allow the dough to soften and come to room temperature.
Dust a clean work surface with flour. Roll the dough out 1/8-inch thick and lay it in the tart pan with lots of overhang on the sides. Schmear half the filling into the bottom of the tart pan and top with the apple mixture. Fold the extra dough over the top of the apples. Brush the dough with the egg wash.
Bake the tart in the oven until the top is golden brown and slightly crispy, 45 to 50 minutes.
This filling is enough for 2 tarts. It's easier to make a larger quantity and it lasts in the fridge for a few days.