Add the frozen berries, banana, peanut butter, Greek yogurt, and sweetener into the blender.
Blinger on high for about 30 seconds until the mixture is bright pink or purple, thick, and smooth.
Stop the blender and scrape down the sides with a spatula to ensure everything is evenly blended.
Blend again until the mixture is velvety, spoonable but not runny—adjust with a splash of milk if needed.
Pour the thick smoothie mixture into a bowl, using the spatula to spread it evenly.
Garnish with extra berries, a drizzle of honey, or granola for added texture and flavor.
Take a moment to enjoy the sweet, nutty aroma and vibrant color before digging in with a spoon.