Peel the parsnips and roughly chop them into large bits. Add them to a pot, cover with water and set on medium-high heat until the water boils. Lower the heat and simmer until fork tender, about 20 minutes.
In the meantime, peel the garlic cloves and, if present, remove the green shoot if sprouted. Chop each half clove into fours. Add to a saucepan with the milk and set on medium-high heat. When it starts to steam, lower the heat to medium-low and cook for 20 minutes stirring from time to time.
When the garlic is soft and the milk has reduced, remove from the stove and add the butter. Stir to melt.
Drain the parsnip and add to a tall container suitable for a hand blender. Pour in the milk and garlic. Blend until smooth. Add ¼ teaspoon salt and stir to dissolve. Taste test before you add the rest, in order to not overpower the sweetness by adding all the salt in one go.
Notes
The nutritional information provided is made with an online calculator and only meant to be used as a guideline.