Layer ingredients in Ninja Creami pint. Add Greek yogurt to the bottom of your Ninja Creami pint container. Break banana into 4-5 chunks and add to the pint. Add frozen mixed berries on top. Drizzle maple syrup over the fruit, then pour milk over everything until you reach just below the max fill line.
Decide your timeline. You have two options here:
Spin immediately: Place lid on loosely and proceed to step 3. This works because the frozen berries keep everything cold enough to spin right away.
Freeze for later: Place in freezer uncovered or with lid sitting loosely on top (not sealed tight) for 24 hours until frozen solid.
Process in Ninja Creami. Remove lid if frozen. Place pint into the Ninja Creami outer bowl and lock it into the machine. Select the "Smoothie Bowl" function and press start. Let the machine complete its cycle.
Check texture and re-spin if needed. Remove the outer bowl and check your smoothie bowl. If the texture appears powdery, crumbly, or icy, use the back of a spoon to flatten and smooth the top surface. Place back in the machine and select "Smoothie Bowl" again to re-spin. This second spin usually creates the perfect creamy texture.
Serve and enjoy. Scoop the smoothie bowl into a serving bowl. Top with your favorite toppings like granola, fresh fruit, nut butter, chia seeds, or shredded coconut. Serve immediately with a spoon.