Preheat the oven to 375⁰F; oil a 12-cup muffin pan; set aside.
Distribute the batter evenly among the 12 cups in the muffin pan. Combine the turbinado sugar and 1/4 teaspoon cinnamon. Sprinkle the cinnamon-sugar over batter and gently pat into the batter.*
*I had forgotten to sprinkle on the cinnamon-sugar prior to baking and did so 7 minutes into baking. It worked as you can see.