Preheat the oven to 350 degrees. Grease the baking dish with some butter. Cream together the butter and sugar. Add eggs 1 at a time. In a separate bowl, sift together flour, baking soda, cinnamon, and salt. Add to the wet ingredients. Alternating with the sour cream and vanilla. Fold in the apples. Pour into a baking dish. In a bowl, combine the sugar, flour (1/2 cup), cinnamon and butter and mix until it looks like course crumbs. Sprinkle the topping over the cake and bake for 35-40 minutes. Remove from the oven and let it cool. To make the glaze, combine the sugar, vanilla and water. Drizzle over the cake.