Combine 1/4 teaspoon salt and next 8 ingredients in a large saucepan. Bring to a boil over medium heat; reduce heat, and simmer, covered, 15 minutes or until potato is tender and liquid is almost evaporated. Remove from heat.
Discard thyme sprig. Stir in remaining 1/4 teaspoon salt, pepper, and half-and-half. Mash with a potato masher until almost smooth.
Note: Though the menu serves 6, this recipe makes enough for 8 servings. Refrigerate the extra servings to enjoy the next day as a side to chicken, beef, or fish.