To make crepes,combine flour, sugar and salt in a food processor and process briefly. With motor running, add milk, water, eggs and butter through feed tube. Process until smooth. Let stand 30 minutes before using.
Make crepes as directed:
IF your pan is not nonstick, film it with a light coat of butter or oil. Heat until you hold your hand an inch away and feel the heat, then ladle in a small amount of batter, about 2 Tablespoons.
Lift the pan and rotate it, swirling a thin, even coating of patter all over the pan. Keep swirling until the batter stops moving.
Set the pan on the burner and cook about 15 seconds, until the top is dry. Using a thin spatula, lift one edge. Using your fingers if necessary , lift the crepe and turn it over, then use your fingers to nudge out any wrinkles.
Cook until the crepe moves when you jerk the pan. Slip out onto waxed paper.
Orange Butter Sauce:
In a large skillet over medium heat, combine butter, oj, sugar, lemon juice and orange zest, if using.
Bring to a boil, stirring to melt sugar, then boil until slightly thickened, 2-3 minutes. Stir in 2 T Grand Marnier and cognac. Return to boil for 30 seconds. Remove from heat.
One by one, place a crepe in the sauce and turn it over to coat. Fold crepe in half, then in quarters. Place on warmed plate with point toward the middle.
continue with each crepe, overlapping each one slightly.
Spoon extra sauce over the crepes.
Heat 1/2 c Grand Marnier briefly in a microwave or in a ladle held over burner. Pour over crepes and ignite with a long handled match, or light in ladle and pour flaming liquor over the crepes.