Add the frozen bananas, peanut butter, flaxseed meal, vanilla extract, and nondairy milk to a high-speed blender.
Blend until smooth and creamy. Stop occasionally to scrape down the sides if needed.
Adjust the consistency by adding a tablespoon of milk at a time. For the thickest Peanut Butter Banana Smoothie Bowl, use as little liquid as possible.
Spoon the smoothie into a serving bowl.
Top with your favorite toppings such as granola, banana slices, fresh berries, chia seeds, coconut, or an extra drizzle of peanut butter.
Serve immediately with a spoon and enjoy.