Adding the blueberries after cooking keeps the oatmeal creamy rather than watery and gives you that gorgeous purple swirl. Frozen blueberries work better than fresh here — they burst and release juice. They're also healthier! Cashew milk makes the oatmeal extra silky; whole milk gives a rich, comforting creaminess. Cinnamon balances the sweetness, stabilizes blood sugar response, and adds warmth.