~From Savoring Time in the Kitchen
For the Crème pâtissière:
1 cup whole milk
1 vanilla bean (I recommend using a vanilla bean but you could substitute vanilla extract)
¼ cup sugar
5 tablespoons cornstarch
3 large egg yolks
1 tablespoon butter
Place milk in medium saucepan over medium heat. Split and scrape the vanilla bean, and add bean to pan along with scrapings. Bring to a boil.
Meanwhile, in separate bowl, beat together sugar, cornstarch and yolks until mixture turns pale yellow. Gradually pour milk into yolk mixture while whisking constantly. Return mixture to medium heat and whisk continually until mixture thickens and just comes to a boil being careful not to let it get too thick. Remove from heat, and whisk in butter. Remove vanilla bean. Pour cream into a bowl, and place plastic wrap directly over the cream. This will prevent a skin from forming while the cream cools. Place in refrigerator to cool.
For the Apple Tart:
1 sheet frozen puff pastry, thawed (or your favorite pie crust recipe)
3-4 Granny Smith apples, depending how their size
1/4 cup granulated sugar
2 teaspoons cinnamon
2 tablespoons butter, melted
Using one sheet of puff pastry dough, unthawed, gently roll it out on a lightly floured surface until it will completely fill a tart pan with removable bottom with enough to cover over the sides slightly. Pat to fit and trim off the excess. Prick the bottom of the tart all over with a fork and bake in a preheated 350 degree oven for 15-20 minutes, or until golden and puffed. Set aside to cool. (If you have enough dough left, you can cut decorative shapes and bake them on another small baking sheet for about 5-7 minutes while the shell is baking)
Cut and core the apples. Using a mandoline or sharp knife, slice them into uniform slices about 1/4 inch thick. Place them in a mixing bowl and add the sugar and cinnamon and toss. Fill the bottom of the tart shell with the cooled Crème pâtissière, spreading to smooth it out evenly. Starting at the outside rim of the baked tart shell, start making a concentric circle with the apple slices, overlapping them slightly. The next row should overlap the first by at least 1/4 inch, keeping in mind that the apples will shrink slightly when they bake. Finish the center by cutting either one large round, thin slice of apple or three smaller ones - enough to fill the center. Brush the top of the apples with the melted butter. Alternatively, you could use apricot jelly or preserves, melted.
Bake the tart in a 375 degree preheated oven for 50 minutes.
Served with sweetened whipping cream (I added a little cinnamon to mine).