Preheat the oven to 350 degrees. Butter a 9-inch springform pan.
Mix the crumbs, brown sugar, butter and vanilla in a large bowl. Press the crumb mixture into the bottom and partway up the sides of the prepared pan. Bake for 8 to 10 minutes, or until lightly browned. Cool completely in the pan on a rack.
To make the filling: Beat the cream cheese, brown sugar, vanilla and butterscotch extracts in a large bowl with an electric mixer at medium speed until creamy. Add the eggs, one at a time, until just blended after each addition. With mixer at low speed, add the sour cream. Add the nuts. Spoon into the baked and cooled crust. Bake for 35 to 45 minutes at 350 degrees, or until set.
To make the topping: With mixer at medium speed, beat the sour cream, sugar and butterscotch extract in a medium bowl. Spread the topping over the cake. Bake for 10 minutes at 350 degrees, or until set. Cool the cake in the pan on a rack. Refrigerate for at least 6 hours.
Source: “Cakes 1,001 Classic Recipes from Around the World”, Readers Digest, 2003