Preheat oven to 375 F.
Peel apples halfway down and core. Toss raisins with water, sugar and breadcrumbs. Fill center of each apple with raisins and place in a baking dish. Sprinkle tops of apples with lemon juice.
Blend oats, sugar, flour, cinnamon, salt and ginger. Cut in butter until topping takes on a dense crumbly texture.
Press generous amounts of crumble on top of each apple.
Bake apples for 20-30 minutes, until tender (check by inserting a skewer or toothpick).
Have ready a strainer over a small bowl before beginning. Heat cream with seeds from vanilla bean and scraped vanilla bean pod until it comes to a gentle simmer.
In bowl, whisk together egg yolk and sugar. Whisking constantly add a little of the hot cream to the egg mixture, and blend completely until all the cream has been added.
Return cream to medium-low heat and stir, using a wooden spoon until sauce thickens and coats the spoon when lifted.
Remove from heat and strain immediately.
Cover and chill until ready to serve.
To serve pour the vanilla custard over the baked apple. For an extra kick, steep your raisins for the center of the apples in 1 1/2 tablespoons brandy or rum!