Combine milk, cinnamon, and soda in a heavy saucepan; cook over medium heat until candy thermometer registers 160°. Discard cinnamon sticks.
Combine sugar, cornstarch, and flour in a large saucepan; gradually stir in scalded milk mixture. Cook over medium heat, stirring constantly, until mixture is thickened and bubbly. Remove from heat.
Beat yolks in a medium mixing bowl until thick and lemon colored. Gradually stir one-fourth of hot mixture into yolks; add to remaining hot mixture, stirring constantly. Cook over medium heat, stirring constantly with a metal spoon, 2 minutes or until mixture coats the spoon. Remove from heat. Add butter, vanilla, and salt; stir until butter melts.
Pour custard into a greased 13- x 9- x 2 - inch baking pan. Cool completely. Cover tightly, and place in freezer overnight.
Cut custard into 1 1/2-inch squares. Dip squares in beaten egg whites; dredge in cracker meal. Fry in deep hot oil (375°) until golden brown. Drain well on paper towels. Sprinkle with powdered sugar. Serve hot.