Pour flour into heavy saucepan.
Slowly add 1 cup milk to form smooth paste.
Add remaining milk, cinnamon, and sugar.
Beat with electric mixer until smooth.
Place mixture over heat.
Cook on high until mixture boils and thickens.
Sangria when mixture thickens remove from flame; beat in vanilla.
Pour custard mixture into 8-inch-square cake pan.
Chill 5 hours.
Remove custard from refrigerator; cut into 2-inch squares.
Melt butter in skillet.
Coat custard with egg, then with crumbs.
Fry in butter until brown on both sides, about 40 seconds on each side.