In another medium-sized bowl, beat white sugar and butter together using an electric mixer until smooth and creamy.
Beat in eggs, 1 at a time, until blended in; add in vanilla extract.
Combine & whisk flour and baking powder together in another bowl and add into creamed butter mixture and stir until blended.
Mix milk into batter until smooth.
Pour half the batter into the prepared loaf pan.
Pour ⅔rds of the cinnamon cream cheese filling on top of the cake batter.
Place the sliced apples in a bowl with the brown sugar/cinnamon mixture and place ½ of them on top of the cream cheese layer.
Add the rest of the cake batter, then add the rest of the cream cheese filling by dollops scattered about, then add the rest of the brown sugar cinnamon coated apples.
Add the brown sugar crumble topping and bake for 50-60 minutes.
Let coffee cake come to room temperature. Serve, keep remainder refrigerated.