Preheat the oven to 350 degrees F. Grease (liberally) or line a muffin tin.
In a large bowl, combine the rolled oats, baking powder, sea salt, and cinnamon. In another bowl, do the same with the maple syrup, beaten eggs, vanilla extract, and milk. Add the wet ingredients to the dry ingredients and mix together.
Fold in the diced strawberries and rhubarb and mix well. Use an ice cream scooper or large spoon to scoop batter into the muffin tin. The cups should be filled to the brim with batter. I like to sprinkle a small amount of brown sugar on top of each muffin before putting them into the oven...highly recommend!
Bake for 35-40 minutes or until the muffins are baked through the center (use a toothpick to test if needed). Remove them from the oven and let them sit in the muffin tin to cool.
Carefully remove each muffin with a spoon or butter knife. Store in a container in the fridge (up to 5 days) or freezer. Enjoy cold or reheat in the microwave. They taste great with a dab of butter or nut butter.
The muffin cups will be very full, almost overflowing, when filling the tin.
Let the muffins cool completely before trying to remove them from the tin. They will fall apart if you try to remove them while warm.
The muffins are meant to resemble the texture of baked oatmeal, not traditional muffins. So they will be moist in the center, chewy, and dense...absolutely delicious!
To make them vegan: sub 2 tablespoons of flax or chia seeds for the eggs, and be sure to use non-dairy milk.
Additions: add ¼ cup chopped nuts (I put some walnuts in a few of mine!) or ¼ cup chocolate chips for an added touch of sweetness.