Simmer Cream with Roasted Garlic: To a small saucepan, add the Half and Half, 2 tablespoons butter, whole sprigs of thyme, and the roasted garlic cloves.Place the pan over medium heat and bring the contents to a simmer. Once simmering, immediately reduce heat to low and allow flavors to seep together, stirring occasionally.
Meanwhile, Saute Leeks: In a dutch oven or large saucepan, melt 2 tablespoons butter over medium heat. Add the leeks and season with salt and pepper. Cook, stirring occasionally, until softened, about 4 minutes. Remove the leeks from the pan and set the leeks aside.
Bring Parsnips and Potatoes to Boil: To the same dutch oven or large saucepan, add the parsnips, potatoes, chicken stock, and enough cold water to cover the vegetables by two inches. Next, generously season the water with enough salt to make the water as salty as the ocean. Place the pan over high heat and bring to a boil. Once boiling, immediately reduce the heat to maintain a gentle simmer.
Simmer Potatoes and Parsnips: Cook until parsnips and potatoes until they're very tender but still hold their shape, about 15 – 20 minutes.
Drain Potatoes and Parsnips: Drain the cooked potatoes and parsnips in a colander. Then return the vegetables to the pot. Place the pot over low heat to cook the potatoes, stirring gently, until they're dry and the moisture is mostly evaporated, about 2 minutes.
Remove Thyme from Warm Cream: Use a slotted spoon to remove the sprigs of thyme from the warmed cream and discard the thyme. DO NOT discard the garlic cloves!
Flavor and Mash Potatoes and Parsnips: Add the leeks and milk mixture with the garlic cloves to the pot with the potatoes. Use a potato mashed or the back of a wooden spoon to combine the ingredients and mash the potatoes to the desired consistency. Taste the mashed purple potatoes and season with salt and pepper to taste.
Serve Mashed Purple Potatoes and Parsnips: Garnish with fresh thyme leaves. Serve immediately while still warm and enjoy.
Notes
Chicken stock adds a lot of flavor to the potatoes, but you can substitute all water if desired.
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Nutritional information is provided as a courtesy and the nutrition facts are an estimate based upon 6 servings. Exact information will depend upon the brands of ingredients and precise measurements used.