Melt butter in a large skillet; add green onions and garlic, and sauté 2 to 3 minutes or until tender. Add spinach; cook, stirring constantly, 1 minute or just until wilted. Stir in parsley, and add to rice mixture. Spoon into 12 lightly greased 10-ounce custard cups or individual soufflé dishes, and place in 2 (13- x 9-inch) pans. Add hot water to pans to depth of 1 inch.
Bake at 350° for 30 minutes or until set. Remove from water; cool on wire racks 5 minutes. Loosen edges with a knife; unmold onto a serving platter. Garnish, if desired.