You can't go past a microwave mug recipe, and this Oat Muffin with Blueberries and Banana Custard will have your taste buds singing in just 7 minutes. Great for breakfast or lunch. According to a few studies, blueberries can help in boosting immunity and may reduce the risk of diabetes, obesity and heart diseases. Moreover, consuming a small portion of berries daily can help in strengthening your metabolism.