Preheat oven to 325 F (160 C, Gas Mark 3)
Stir together apples, raisins, lemon juice, and ginger.
In skillet, melt butter over high heat; add apple mixture and cook for a few minutes.
Stir in 2 tbsp. of the sugar. Cook for a few minutes until the apples are caramelized.
Divide apples amongst six 1 cup ramekins which have been oiled.
Place milk in a medium saucepan. Set over medium heat and heat milk until it bubbles. Take some hot milk and add to the eggs, mix and then pour the egg mixture into the saucepan, whisking constantly until thoroughly blended, add the remaining sugar and keep mixing over heat until the mixture starts to thicken a bit. It should look like a sauce. Add the nutmeg, vanilla, and mix well. Pour over apple mixture.
Prepare a warm bain-marie to cook the custard
Set the ramekins inside large roasting pan and Prepare a bain-marie (water bath) by pouring enough boiling water in the roasting pan to come halfway up sides of ramekins. This will gently cook the custard.
Place in the pre-heated oven for 45 to 50 minutes or until custard is set but still jiggly. Carefully remove baking dish to cooling rack.
Run a knife around the edges and invert on a serving plate. Sprinkle with walnuts.
Cool to room temperature before serving.