Mash the bananas: In a bowl, mash 1–2 ripe bananas until mostly smooth. Leave a few small chunks if you like texture.
Stir in the wet ingredients: Add 3/4 cup milk, 1/2 cup vanilla Greek yogurt, and 1/2–1 scoop vanilla protein powder. Whisk until no lumps remain.
Add 1/2 teaspoon vanilla extract and a pinch of salt.
Add chia seeds: Stir in 3 tablespoons chia seeds. Mix well so no dry clumps stick to the sides. Let it sit for 5 minutes, then stir again to prevent clumping.
Sweeten to taste: If needed, add 1–2 teaspoons maple syrup or honey.
Taste and adjust sweetness now since flavors mellow as it chills.
Chill: Cover and refrigerate for at least 2 hours, ideally overnight. The chia seeds will thicken the mixture to a creamy, spoonable consistency.
Build the “pie” experience: Before serving, give it a stir. Layer with sliced banana and a sprinkle of graham cracker crumbs or vanilla wafer crumbs.
Add a dollop of whipped topping or a spoonful of yogurt. Finish with a dusting of cinnamon if you like.
Serve: Enjoy straight from the fridge. If it’s too thick, stir in a splash of milk to loosen it.