In small mixer bowl beat together all orange butter ingredients at medium speed, scraping bowl often, until light and fluffy (1 to 2 minutes); set aside.In pie pan stir together milk, eggs and 1 teaspoon orange peel.In 10 inch skillet or griddle melt 2 tablespoons butter over medium heat.Dip 4 croissant halves into egg mixture, turning to coat both sides.
Place croissant halves, cut side down, in skillet. Cook, turning once, until golden brown (3 to 4 minutes on each side).
Remove to serving platter; keep warm.Repeat with remaining 2 tablespoons butter and 4 croissant halves. Dust croissant halves with powdered sugar; serve with orange butter.