Use old-fashioned rolled oats for best texture; quick oats get mushy. Cold brew coffee is smoother than espresso but either works. Greek yogurt adds creaminess and protein; substitute with coconut yogurt for dairy-free. Adjust sweetness with maple syrup or honey. Store in airtight containers up to 4 days. Warm gently if preferred. Add more oats or reduce milk if mixture is too watery. Variations include adding cardamom and cloves for chai twist, cocoa powder for mocha flavor, or nuts for crunch.