Combine all ingredients in a blender (or use an immersion blender with a designated jar) and blend on high speed until all ingredients are combined, the mixture is smooth and frothy.
Pour into a mug, add a dash of cinnamon (optional) and enjoy!
Notes
Milk
I like a smaller, stronger coffee so I'm not using much milk. For a larger protein coffee, add more milk to your taste.
Use any milk that you like. Dairy milk and soy milk will give you the best results, but almond milk or other alternatives work nicely too.
Variations
You can use cold brew coffee to make an iced protein coffee that you serve over ice.
To make a coffee shake, use more milk. If you want a hot protein shake, warm up milk before adding the rest of the ingredients.
To make a frappe, blend the ingredients with a cup of ice and add more milk if needed.
To make a smoothie, add a banana, some ice and more milk.