Mix the wet base: In a medium bowl or large jar, whisk 1 cup milk, 1/2 cup Greek yogurt, 1 scoop protein powder, 1 teaspoon vanilla extract, 1–2 teaspoons sweetener, and a pinch of salt until smooth.
If the protein clumps, whisk longer or use a small blender for 10 seconds.
Add the chocolate note: Whisk in 1–2 teaspoons unsweetened cocoa powder. Start with less; you can always add more after tasting.
Stir in chia seeds: Add 3 tablespoons chia seeds and whisk well. Let it sit for 2–3 minutes, then whisk again to break up any clumps.
This second stir keeps the pudding smooth.
Crush the cookies: Place 2 chocolate sandwich cookies in a small bag and crush with the bottom of a glass. Aim for a mix of crumbs and small chunks for texture.
Fold in the crumbs: Stir most of the crushed cookies into the chia mixture, reserving a teaspoon or two for topping.
Chill to thicken: Cover and refrigerate at least 2 hours, ideally overnight. The chia seeds will swell and create a pudding-like texture.
Adjust before serving: Give it a good stir.
If it’s too thick, add a splash of milk; if it’s too thin, stir in 1 more teaspoon chia and rest 10–15 minutes.
Finish and serve: Spoon into bowls or jars, top with reserved cookie crumbs, and add any optional toppings like mini chips or a small dollop of whipped topping.