Preheat oven to 375. Combine all the dry ingredients: flour, sugar, chia seeds, baking soda, and salt in a large mixing bowl. Add in oatmeal, milk, oil, vanilla extract, and egg and stir to combine until the batter is moist. Add in the boiling water and stir to mix and let it stand for 15 minutes
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 3/4 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