Preheat oven to 350°F (180°C). Spray a mini muffin pan well with canola oil spray. (Assumption: oven temperature.)
In a bowl, whisk flour, baking powder, and salt.
In a second bowl, whisk eggs and sugar until combined. Whisk in oil, vanilla, and milk.
Whisk in the melted butter (slightly cooled) until smooth.
Add dry ingredients to wet and whisk just until smooth and no flour streaks remain.
Fill each mini muffin cavity about 3/4 full.
Bake 10–12 minutes, until tops spring back and a toothpick comes out clean (or with a few moist crumbs). (Assumption: bake time.)
Mix the cinnamon and sugar in a bowl.
Cool muffins 2–3 minutes, remove from pan, lightly mist with oil spray, then roll in cinnamon sugar while warm.
Serve warm or cool completely before storing.