If your ice cream is still very thick after blending, it may be because of the protein powder. Especially vegan protein powder and casein tend to absorb plenty of moisture. Fixing a thick ice cream with protein powder is very simple. All you should do is blending in one or two tablespoons of your favorite milk until it reaches a soft serve consistency. My recommendations are unsweetened almond milk, soy milk, oat milk and coconut milk.