Choose your base. In a medium bowl, add the Greek yogurt and protein powder. If using cocoa or espresso powder, add it now.
Mix the dry and creamy. Stir with a spoon or small whisk until the protein is mostly incorporated.
It will look thick and slightly chalky at first—this is normal.
Add liquid slowly. Pour in 3 tablespoons of milk and whisk. Keep adding milk 1 tablespoon at a time until you reach your preferred texture: less milk for thick and spoonable, more milk for silky and pudding-like.
Sweeten and flavor. Add the vanilla, sweetener, and a pinch of salt. Taste and adjust.
If it tastes flat, it usually needs a touch more sweetener or salt.
Chill or warm. For classic thick custard vibes, chill 10–20 minutes. For a warm, dessert-like bowl, microwave in 10–15 second bursts, stirring between each, until just warm and smooth. Do not overheat or it may split.
Finish with texture. Top with berries, nuts, or a drizzle of nut butter. Serve immediately or refrigerate for later.