I do unflavored, unsweetened whey protein and then add my own flavors and sweeteners. I sweeten with Kal brand stevia (no after taste) put some almond, hazelnut, coconut or other extract or perhaps no-sugar chocolate syrup and add some low-carb ice cream if I want to make it thicker. Mix with a hand blender.

I don't make them anymore, but for years they were a meal substitute for me.

I also did soy protein for a while (it comes out thicker) but it had to be non-GMO soy and that is sometimes hard to find.

Bob