Add the banana, milk, egg, coconut oil, and vanilla to a medium bowl. Stir to combine.
Stir in the flour, baking powder, cinnamon, and salt. (The batter will be thick.)
Warm the waffle iron and use about 1/3-cup batter for each waffle. Place the batter into the center of the waffle iron, spread it a little with a spoon, and close the lid. Let cook according to the waffle iron's settings. (My waffle iron has a 1-5 heat setting and I use the heating setting 4.)
Serve immediately or place onto a baking sheet and keep in a 200 degree oven while you finish cooking the rest of the batch.
Serve warm with syrup, fruit, jam, applesauce or nut butter.
Notes
Let leftovers cool completely and store in a container in the fridge for up to 3 days. Pop into the toaster to warm. Or, freeze in a freezer bag and warm on a future morning.
Egg-free: Omit the egg, increase the milk to 3/4 cup, and soak 2 tablespoons chia seeds in the milk for 5 minutes before adding to the batter.
Gluten-free: Use cup-for-cup style gluten-free flour.
Dairy-free: Use coconut oil and nondairy milk.
Serve with maple syrup, fruit puree, applesauce, or yogurt for dipping.
Chocolate Banana Waffles: Swap in 1 tablespoon unsweetened cocoa powder for 1 tablespoon of the flour. Or add a handful of chocolate chips to the batter.