Preheat oven to 350 degrees F

In the bowl of a stand mixer (or in a bowl with an electric mixer), combine butter and ⅔ cup sugar' mix until creamy. Add eggs, one at a time, mixing well after each addition. Add vanilla, mix. Removing the bowl from the stand mixer, add the flour and baking powder, and stir by hand with a wooden spoon or spatula until just combined. Add the milk and using a fork, stir until well incorporated and smooth. Set aside.

Place apple pieces into a medium sized bowl and sprinkle 2 TBS sugar and 1 teaspoon cinnamon over the top. Toss well with hands until evenly coated. Set aside.

In a small bowl combine ¼ cup brown sugar and ½ teaspoon cinnamon. Use a fork to get all the chunks out and mix well, set aside.

Spray a 12 muffin tin with nonstick spray and line with cupcake wrappers (optional, but definitely spray regardless). Place a heaping TBS of batter into the bottom of the wrapper, top with a heaping TBS of apples, sprinkle brown sugar/cinnamon over the top of apples (about 1 tsp), then top with another heaping TBS of batter. Finish with a regular TBS of apples over the top of the batter. Repeat for all muffins.

Place in center of preheated oven and bake for 20-25 minutes or until cooked through. Put a toothpick into the middle and it should come out without moist batter on it.

In a small bowl mix powdered sugar and 2 TBS milk. Drizzle over the top of the muffins and serve!