Saute onion until very soft. Measure water for stuffing plus 1 - 2 Tbs extra water into a saucepan and bring to boil, adding butter or whatever the stuffing package says. Remove from heat. Add onion, chicken and stuffing crumbs. Stir very well. Let stand 5 minutes. Spread out on sheet pan or cookie sheet in a thin layer and place in freezer 10 -15 minutes until thoroughly and completely cooled.
Mix crepes ingredients well. Batter should be smooth. Strain through fine mesh strainer if necessary. Use a skillet with a 6” diameter at the base. Rim diameter may be larger. Measure at the base, on the inside. Preheat skillet over medium heat. Spray with cooking spray like Pam and wipe generously with vegetable oil using a paper towel. Skillet should be lubricated but not full of oil. Add about 1/4 to 1/3 cup batter to heated skillet. Rotate skillet to distribute batter over entire bottom. Remove crepe from pan when edges are quite dry and batter is thoroughly set in the center. Batter will change from shiny to more matte as it cooks. Cook until whole crepe is matte. Also, pinholes will cover the entire surface of a fully cooked crepe. Bottom of crepe should not be browned. Cool crepes on paper towels. It’s OK to layer them with paper towels in between. Spray skillet with cooking spray every 2 or 3 crepes. Wipe with vegetable oil after every crepe. Thoroughly remove anything that sticks to the skillet.
Place about 1/4 cup stuffing into each crepe and roll up. Roll should be 1/2 to 3/4 inch in diameter. Trim unfilled ends of rolls, if desired. Yield should be about 26 rolls.
Stir sauce ingredients together over medium-low heat. Do not let it get too hot. Needs to be just warm, not hot for assembly.
Skim coat bottom of 2 13 x 9 baking dishes with sauce. Arrange rolls in single layer in each dish. Pour remaining sauce over rolls, dividing sauce equally between the two dishes. Cover with foil. Spray inside surface of foil with cooking spray.
Bake at 350 for 50 to 60 minutes.