Preheat oven to 350.
To make your filling beat together your cream cheese, sugar, egg and vanilla and mix until creamy. Fold in your chopped candy bar and set aside.
Meanwhile, in large bowl beat together your butter and sugar until light and fluffy, add eggs one at a time and beat until blended.
Mix in your sour cream and vanilla until combined.
Slowly add your flour and baking powder and continue beating until all mixed together.
Grease a 9x13" pan with non-stick cooking spray and add about half of your batter to the bottom of pan (batter will be thick so spread as good as you can).
Spread your filling over the cake batter.
Drop dollops of the remaining batter over the top, then using a butter knife spread over to make sure all is covered.
In bowl combined all your topping ingredients and using a pastry blender or two forks blend until crumbs form.
Sprinkle over the top of your cake and bake for about 50-60 minutes or until center is set.
Remove from oven and let cool slightly, while cooling mix your glaze ingredients together in bowl.
Drizzle your glaze over the top, cut and serve.