Gently melt the white chocolate: In a small saucepan over very low heat, warm 1/2 cup milk with 1–2 ounces of white chocolate. Stir until smooth.
Don’t let it simmer. Remove from heat and cool for 5 minutes.
Mix the base: In a bowl, whisk the remaining 1 1/2 cups milk, Greek yogurt, protein powder, vanilla, sweetener (if using), and a pinch of salt. Whisk until no lumps remain.
Combine with chia: Pour in the cooled white chocolate milk, then add chia seeds.
Whisk well for 30–45 seconds to separate the seeds.
First rest and whisk: Let the mixture sit for 10 minutes, then whisk again to break up any clumps. This step ensures an even, creamy texture.
Fold in raspberries: Gently stir in raspberries. If you like swirls, lightly mash a few with a fork and fold through.
Add lemon zest if using.
Chill: Cover and refrigerate for at least 2–3 hours, ideally overnight. The pudding will thicken as the chia absorbs the liquid.
Adjust and serve: Stir before serving. If it’s too thick, loosen with a splash of milk.
Taste and add a touch more sweetener if needed. Top with extra raspberries or shaved white chocolate.