Heat oven to 375°F. Cut thawed cinnamon rolls into about 6 sections each.
Place melted butter into ungreased 11x7-inch glass baking dish. Placed chopped cinnamon roll pieces in dish with melted butter. Coat cinnamon rolls with butter
In medium bowl, beat eggs. Beat in milk , cinnamon and vanilla until well blended; gently pour over roll pieces. Allow casserole to proof for about 30 minutes. Drizzle with 1/2 cup syrup.
Bake 20 to 28 minutes or until golden brown. Cool 15 minutes. Meanwhile, remove icing; let come to room temperature or until thin enough to drizzle.
Drizzle icing over top; sprinkle with powdered sugar. Serve with the additional 1/2 cup maple syrup.