Mix the base: In a jar or bowl, combine 1/2 cup rolled oats, 2/3 cup milk, 1/3 cup Greek yogurt, 1 tablespoon chia seeds, and 1 scoop vanilla protein powder.
Flavor it: Stir in 1/2 teaspoon vanilla extract, a pinch of salt, 1–2 teaspoons cocoa powder (optional), and 1–2 teaspoons maple syrup or honey if you like it sweeter.
Add the cookies: Gently fold in 1–2 crushed chocolate sandwich cookies.
Save a little for topping.
Adjust texture: If the mixture seems too thick, add a splash more milk. It should be pourable but not watery.
Chill: Cover and refrigerate at least 4 hours, ideally overnight, to let the oats soften and thicken.
Finish and serve: In the morning, give it a stir. Top with remaining cookie crumbles and a few mini chocolate chips or cacao nibs if you like.
Enjoy cold.