Place the frozen berries, banana, peanut butter, jelly, Greek yogurt, and milk into a high-speed blender.
Blend on high for about 30-45 seconds, stopping to scrape down the sides if needed, until the mixture is thick, smooth, and vibrant in color.
Check the consistency; if it’s too thick, add a splash more milk and pulse again until smooth. If it’s too thin, toss in a few more berries and blend briefly.
Pour the thick, velvety mixture into a wide bowl and use a spatula to smooth the surface for an even presentation.
Decorate with sliced bananas, a drizzle of jelly, granola, or chopped nuts to add color and texture.
Serve immediately with a spoon, enjoying the cold, creamy, and vibrant breakfast that’s both nostalgic and nourishing.