Preheat oven to 375. Combine all the dry ingredients: flour, sugar, baking soda, and salt in a large mixing bowl. Beat the egg with sour cream and add in the mixture. Add in oatmeal cereal, breast milk, vanilla extract and stir to combine until the batter is moist
Gently stir in the blueberries and chocolate morsels to combine. Prepare the muffin trays by spraying with non-stick cooking spray. Spoon batter into the muffin cups (about ¾ of the cups as it will rise). Pop into the oven and bake for about 25 minutes (longer on my oven) or until the toothpick inserted in the middle comes out clean. Remove from the oven and transfer to a wire rack to let them cool down