For crepes: In a large bowl, combine 4 eggs, 1 1/3 cups milk, melted butter, 1 cup flour, 2 tablespoons sugar and 1/2 teaspoon salt. Stir until smooth. In a medium skillet or crepe pan over medium-high heat, spoon a few tablespoon of batter and tilt pan to cover completely. Cook, turning once, until golden, 2 minutes. Repeat to make 6 crepes.
For filling: In a medium saucepan over medium-high heat, combine 1 cup sugar, 3 tablespoons flour and 1/4 teaspoon salt. Gradually stir in 2 1/4 cups milk and chocolate, until chocolate melts and mixture thickens. Remove from heat and stir in 3 eggs. Return to heat and cook 2 minutes more, stirring constantly, until mixture coats the back of a metal spoon. Remove from heat and stir in vanilla and 2 tablespoons butter. Fold in cookie pieces.
Line a 12x15 inch loaf pan with two or three overlapping crepes. Pour filling into lined pan. Cover with two or three crepes. Wrap tightly in plastic wrap and refrigerate 8 hours or overnight.
To serve, place pan in hot water for 1 minute. Remove plastic wrap and place serving plate over pan. Grip pan and plate and invert. Remove pan. Frost if desired.