Begin by preheating the oven to 375. Line 12-14 muffin cups with paper liners and spray them lightly with non-stick baking spray.
In your large mixing bowl, use a fork to mash the overripe bananas. Add the melted butter, maple syrup, plant-milk, vanilla, cinnamon, baking powder, baking soda, and salt together. Add the flour and oats and mix until a batter forms.
Fill each muffin mold ½ way with batter. In a small separate bowl, make the cinnamon swirl by mixing the melted butter, brown sugar, and cinnamon together. Drizzle the cinnamon swirl over the top of the batter and then fill each muffin mold with the remaining batter.
Bake the cinnamon roll banana muffins in the oven for 30 minutes or until they are golden brown. While the muffins bake, use a whisk to mix the melted butter, powdered sugar, and cream cheese to make the cream cheese frosting. (optional)
Drizzle the frosting over the muffins once they have cooled for a couple of minutes and enjoy while it's still warm!