Preheat the oven 350℉. Lightly spray a muffin pan and set aside.
In a large bowl, mix together the flour, baking powder, baking soda, salt and 1 tsp ground cinnamon.
In a separate bowl, mix together the eggs, yogurt, brown sugar, oil and vanilla until smooth.
Slowly mix the dry ingredients into the wet ingredients until just combined.
Divide the batter into the prepared muffin pan and bake in the preheated oven for around 15 minutes, or until a toothpick inserted into the center of a muffin comes out clean. Allow to cool in the pan for around 5 minutes before transferring to wire racks to cool completely.
In a small bowl, combine the sugar and cinnamon. Dip each muffin into the melted butter, then dip in the cinnamon sugar.