Like a lot of vegetables, I think roasted parsnips are in a completely different category than their boiled cousins. To boost the caramelized flavor, I've also roasted onions and apples (tart Granny Smith to offset some of the intense sweetness) before pureeing all three together in the food processor. Honey lets you adjust the flavor to your liking and the whisky gives the rustic side dish a grown up twist - but if you're serving kids, just omit it. —lifeaswecookit
Arrange racks in upper and lower thirds of the oven. Heat oven to 375?F. Line two rimmed baking sheets with aluminum foil.
Peel and trim parsnips. Cut tips from parsnips into 3/4" pieces. Quarter parsnips; remove the cores (don't worry too much if a bit remains). Cut into 3/4" pieces. Place on first baking sheet. Halve onions and cut into large cubes. Place on second baking sheet. Peel apples; remove cores and cut into 3/4" cubes. Place on baking sheet with onions.
Drizzle each pan with 1 tablespoon olive oil; season with salt and pepper. Bake 15 minutes; using spatula, flip fruit and veggies. Place pans back in oven, rotating racks. Bake 15 minutes more, or until softened and just golden brown. Immediately transfer parsnips, apples and onions to food processor.
Meanwhile, in small saucepot on medium-low heat, warm milk and butter. Add 1 cup milk to food processor; process 2 minutes, or until mostly smooth, adding more milk if necessary. Add honey and whisky and process just until combined. If you like added texture, you could stir in 1/2 cup toasted chopped pecans at this point.
Transfer to serving bowl; drizzle with honey and garnish with toasted pecans, if desired.