Whisk together the flour, baking powder, salt, brown sugar, sugar, and cinnamon in a large mixing bowl.
In a separate bowl, add the melted butter (½ cup), eggs, milk, and vanilla extract. Whisk until combined.
Combine the wet and dry ingredients until just moistened. Do not over mix.
Line a muffin pan with liners or spray with nonstick spray. Add ¼ cup of batter to each cup.
Bake the muffins at 350 degrees for 15-20 minutes.
Let the muffins cool for a couple of minutes, then transfer to a cooling rack.
Cinnamon Sugar Coating: Mix the remaining 1 cup of sugar and 4 teaspoons of cinnamon in a shallow bowl. Melt the butter and add it to another shallow bowl. Dip each muffin in butter then in the cinnamon sugar mixture, coating completely.