1. Melt 1 tablespoon of butter in a large skillet over medium heat. Cook parsnips in a single layer until just golden on the bottoms, 8-10 minutes.
2. Flip parsnips, and add apples, water, and 1/2 teaspoon salt. Raise heat to medium-high, and simmer, covered, until parsnips and apples are very soft, 15-20 minutes.
3. Remove from heat and let stand, covered to retain moisture, until slightly cooled, about 5 minutes. Puree mixture in a blender until smooth. With blender running, add remaining 1/2 tablespoon butter. Serve warm.