Turn oven to 165 C (325 F). Coat muffin cups with butter.
Peel parsnips; leave whole. Steam until tender, 5-10 minutes; drain. Mash in a food processor or put through a food mill. There should be about 400 ml (1.75 cups). Let Cool. Beat eggs and milk until blended; stir in bread crumbs, salt, and orange rind; add parsnips. Turn into 12 mini -muffin cups; place n a pan of hot water that comes halfway up the muffin pan. Bake in preheated oven 160 C (325 F) oven until a knife inserted in center comes out clean, about 22 minutes. With a small spatula, loosen edges; turn out. Garnish, if desired, with orange slices and parsley sprigs. Freeze leftovers. Thaw and reheat to serve future meals.