Preheat oven 350°F. Lightly spritz a muffin pan with cooking spray. Even if you use liners, give them a spray as they muffins will tend to stick.
In a large mixing bowl, whisk together the smashed bananas, milk, and vanilla.
In a smaller mixing bowl, stir together the oats, flax meal, baking powder, salt and cinnamon until evenly distributed.
Pour the dry ingredients into the wet ingredients and stir until well combined.
Stir in the strawberries and chocolate chips (if using).
Fill the cavities in the muffin pan to the top with the oatmeal mixture and press down firmly to make them compact.
Bake for 20 to 25 minutes until the edges are golden brown and the oatmeal is baked through and set.
Let cool in the pan on a wire rack for at least 10 minutes.This will ensure that the oatmeal muffins settle and hold together.
Take the oatmeal out of the muffin pan and continue cooling them on the rack.