Mashed Potatoes with parsnip

4 russet potatoes , about 2 lb total, peeled and cut into rounds 1/4 inch thick 3 parsnips , about 3/4 lb total, peeled and cut into rounds 1/4 inch thick 4[...]

6 tablespoons butter 3 large onions , halved and sliced 2 tablespoons chopped fresh rosemary or 2 teaspoons dried rosemary 6 parsnips or 6 turnips or 6[...]

4 russet potatoes , about 2 lb total, peeled and cut into rounds 1/4 inch thick 3 parsnips , about 3/4 lb total, peeled and cut into rounds 1/4 inch thick 4[...]

6 tablespoons butter 3 large onions , halved and sliced 2 tablespoons chopped fresh rosemary or 2 teaspoons dried rosemary 6 parsnips or 6 turnips or 6[...]