In a saucepan over medium heat, bring carrots and water to a low boil for 15 minutes or until carrots are tender. Reserve 1/2 cup of the water.
Place the carrots in a blender, add in the ginger, butter, and season with salt and pepper. Add in 2 tbsp of the reserved water at a time and blend until smooth, scraping down the sides of the blender and adding more water as needed (the consistency should be firm, not watery or runny). Season with salt and pepper to taste.