Heat oven to 375 degrees. Spray a muffin pan (12 muffin cups in the muffin tin) with nonstick cooking spray. Or you can also use parchment paper liners or muffin liners.
In a medium bowl add the sugar, oil, and eggs and stir with wire whisk until combined well.
2/3 cup granulated sugar, 1/2 cup vegetable or canola oil, 2 large eggs
Add in the mashed bananas and vanilla extract. Whisk until combined.
2/3 cup mashed ripe banana, 1 teaspoon vanilla extract
Add in the flour, baking soda, cinnamon, and salt. Stir together with a rubber spatula just until combined and no flour streaks remain in the batter.
1 ⅔ cup all-purpose flour, 1 teaspoon baking soda, ½ teaspoon ground cinnamon, ½ teaspoon salt
Divide the muffin batter evenly among the muffin tins - each muffin cup will be almost to the top, a little over 3/4 full.
Bake for 16 to 21 minutes or until a toothpick inserted into the center comes out clean and the muffins are high and rounded on top. The tops of the muffins should not look wet (that means they're not fully cooked), and they should spring back when lightly pressed with your finger.
Remove the muffin pan from the oven and let them cool for 5 minutes inside the pan and then remove the muffins to a cooling rack. Let the muffins cool enough so that you can touch and hold them.
Dip The Muffins : Combine the sugar and cinnamon in a small bowl. Put melted butter in a separate small bowl. Dip muffin tops into melted butter and then into the cinnamon sugar mixture. Serve warm or let cool completely.
3 tablespoons salted butter, 1/4 cup granulated sugar, ½ teaspoon ground cinnamon