Preheat oven to 350 degrees and grease an 8 inch springform pan.
To make the crumb topping: combine the dry ingredients. Add the melted butter and vanilla. Mix until all is combined and moistened. Set aside.
To make the cake: Cream together the 4 tbsp butter with 1/2 cup sugar in large bowl until fluffy. Add egg, vanilla, and sour cream. Stir to combine. In a separate bowl, stir together the 1 cup flour, baking soda, salt, and baking powder. Add to butter mixture and stir until just combined.
Spread 1/2 of batter into prepared springform pan.
Spread apple chunks evenly over batter followed by one cup of the crumb topping.
Spread remaining batter on top of apple/crumb mixture ending with the remaining crumb topping.
Place pan into preheated oven and bake for 40-50 minutes, or until toothpick comes out clean once inserted into center of cake.
While cake is baking, make the glaze by combining the apple cider and powdered sugar.
Once cake is baked, remove from oven and drizzle glaze evenly on top. Serve and of course, enjoy!!