Whisk the wet base: In a medium bowl, whisk the Greek yogurt, milk, vanilla extract, and sweetener until smooth.
Add the protein powder: Sprinkle the protein powder over the mixture and whisk slowly to incorporate. Keep whisking until no lumps remain.
Balance the flavor: Add a pinch of sea salt. Taste and adjust sweetness or vanilla as needed.
Thicken if desired: For a thicker set, stir in chia seeds and let the mixture sit for 5 minutes, then whisk again.
If using a cornstarch slurry (1 teaspoon cornstarch mixed with 1 tablespoon cold milk), whisk it in thoroughly.
Chill: Cover and refrigerate for at least 30–60 minutes. This lets the flavors meld and the texture set to a classic pudding consistency.
Serve: Stir once more, then spoon into bowls. Add your favorite toppings and enjoy.