Line a 12-cup muffin tin with paper muffin liners. Preheat oven to 400° F.
Stir together the flour, baking powder, baking soda and salt in a large bowl.
In a separate bowl, whisk together the eggs and brown sugar. When fully combined, add the melted butter and continue whisking until the mixture is frothy and creamy. Stir in the applesauce until fully incorporated.
Add the flour mixture to the applesauce mixture and fold it in until it is just incorporated, do not over mix.
Divide the batter evenly amongst the cups, so that they are approximately ¾ full.
In a small bowl, combine the topping ingredients. Sprinkle the sugar mixture on the tops of each muffin.
Bake for 18-20 minutes, until muffin tops have puffed and browned and a toothpick inserted into the center comes out clean.
Remove from oven and allow to cool in the pan slightly before removing.