Cream the butter, sugar and vanilla together. Add the flour and mix until it resembles coarse crumbs. Press into a 9-inch (22cm) springform pan. Spread jam on the bottom and set aside. Pre-heat oven to 400°F (200°C).
Mix ingredients together and spread evenly over the base.
Toss the peeled apples with the sugar and cinnamon and arrange gently on top of the filling. Sprinkle with the chopped walnuts.
Bake at 400°F (200°C) for 10 minutes. Reduce heat to 350°F (180°C) and continue to bake for 30 minutes or until apples are tender. Cool & serve.