Prepare the Oven and Pan: Preheat the oven to 350°F (175°C), then spray the wells of a regular-size muffin pan with non-stick spray.
Combine the Dry Ingredients: Add the oats, baking powder, ground cinnamon, and brown sugar to a large mixing bowl and stir to combine.
Add the Wet Ingredients: Pour in the applesauce, milk, eggs, melted butter, and vanilla extract, then mix until the ingredients are well combined.
Fold in the Fruit: Add the blueberries to the oatmeal mixture and gently stir them through, taking care not to overmix.
Fill the Muffin Pan: Spoon the mixture evenly into the 12 prepared muffin wells, filling each one about three-quarters full.
Bake the Oatmeal Cups: Place the muffin pan in the preheated oven and bake for 20–25 minutes, or until the oatmeal cups are golden brown and set.
Cool in the Pan: Remove the pan from the oven and allow the oatmeal cups to cool in the muffin pan for about 5 minutes.
Finish Cooling: Transfer the oatmeal cups to a baking rack and let them cool completely.
Serve: Serve the baked oatmeal cups with a drizzle of maple syrup and fresh fruit.