Preheat oven to 375 degrees.
In a large bowl, mix together all-purpose flour, salt, baking powder and cinnamon.
Fit your mixer with the paddle attachment. In the bowl of your stand mixer, add softened butter, brown and white sugars. Beat until fluffy. Mix in eggs and vanilla extract. Mix in applesauce, yogurt, and milk.
Remove bowl from mixer and gently fold in flour mixture until well combined.
(This recipe makes about 48 mini muffins, you can bake in two batches or one using two pans.)
If using a metal mini muffin pan, lightly oil each cup. If using a silicone mini muffin pan, you can skip oiling. Fill each muffin cup until just about full. Repeat until all batter is used up.
Bake in preheated oven for 11-13 minutes. When done, a toothpick will run through the muffin and come out mostly clean. When done, allow muffins to lightly cool before transferring to a cooling rack.
While the muffins bake, mix cinnamon sugar in a small bowl.
Once your muffins have cooled, transfer muffins to a large plate or bowl. Gently baste or toss in melted butter. Then, sprinkle generously with cinnamon sugar. Enjoy!