Add the potatoes and carrots to a sauce pan and cover with water. Bring the water to a boil and simmer until the potatoes are extremely soft, about 15 minutes.
Using a slotted spoon, transfer the potatoes and carrots to a high speed blender. Add in 1/2 cup of the cooking water from the pot along with the remaining ingredients.
Blend on high for about 45 seconds until the sauce is smooth and creamy.
Serve immediately or store in a covered container in the refrigerator for up to 3 days.