To make a Grimace Shake similar to McDonald's, blend about 3 scoops of vanilla ice cream, 1 cup of frozen blueberries, ½ cup fresh raspberries, and ½ cup milk. For the iconic purple color, you can add ½ teaspoon of blue spirulina or butterfly pea powder, or optionally a few drops of purple food coloring. Blend everything until smooth, then serve the shake in a glass. Garnish with whipped cream and sprinkles if desired. Here is a simple step-by-step process:

• Let the ice cream soften for easier scooping.
• Add vanilla ice cream, frozen blueberries, fresh raspberries, milk, and the color enhancer (blue spirulina or similar) to a blender.
• Blend until smooth and fruity.
• Pour into a glass or glasses.
• Top with whipped cream and sprinkles for garnish.

This recipe is a popular homemade version of the viral Grimace Shake and captures the berry flavor and purple color well.