Preheat oven to 400° and line two muffin pans with paper muffin liners, or grease the muffin pan really well with butter or cooking spray.
Melt the butter in the microwave or a small sauce pan and set aside to cool slightly.
Whisk together flours, cinnamon, baking soda, baking powder, and salt in a medium sized bowl and set aside.
With a whisk or hand mixer, mix the sugar and melted butter together until combined.
Add in eggs and vanilla. Continue beating until well incorporated.
Next, add in the applesauce and sour cream and beat again with the whisk or mixer until well blended.
Pour the wet ingredients into the dry ingredients and mix on low or with a wooden spoon until the batter just comes together.
Let the batter sit 5-10 min for the flour to hydrate.
Divide the batter into 14 muffin cups--about a 1/3 cup of batter in each cup.
Bake the muffins at 400° for about 17-20 min. The muffins are done when an inserted toothpick comes out clean.
Once baked, set the muffins aside for about 15-20 minutes, until they're cool enough to handle and can be lifted out of the pan.
For the topping: Melt 1/4 cup of butter in a small sauce pan or in the microwave. Transfer to a small dish with an opening slightly wider than the top of the muffins.
In another small dish, combine the 1/2 cup + 2 tablespoons of sugar and the 1 1/2 teaspoons of cinnamon. Mix well.
Once the muffins are cool enough to pick up and not fall apart, dip the tops in the melted butter. Let any excess butter drip off back into the dish.
Immediately dip the buttered top in the cinnamon sugar mixture, rolling the top around to get every nook and cranny coated in the sugar mixture. Set aside and repeat with remaining muffins.
Serve warm and store any leftovers in an airtight container at room temperature.