Cannelloni Stuffed with Asparagus

Prepare pasta sheets by cutting into 6 inch squares (or much smaller if serving as a first course). Bring a large pot of water to boil. Add about 1 tbl. salt. Put a large bowl of cold water with about 2 tbl. of olive oil added next to the pot. When water reaches boiling point, put pasta squares into pot, one by one and cook until al dente, no longer than 2 minutes. Using a slotted spoon transfer each piece of pasta to the bowl of cold water to cool. Dampen a dish towel and spread it out on the table. Remove each piece of pasta from cold water and place it on the damp towel. Allow to rest for about 20 minutes before stuffing. If the need arises to let them rest longer, cover with a second damp towel. Soak the asparagus in a bowl of cold water for about 20 minutes, then cut them into 1 1/2 inch pieces, discarding the white part. Do not scrape the asparagus. Bring a large pot of cold water to a boil. Add salt to taste, then add the asparagus and boil for 2 minutes. Drain the asparagus in a colander and cool under cold running water. Heat 4 tbl. of butter and the olive oil in a saucepan over medium heat. When the butter is completely melted, add the asparagus and saute for 10 minutes. Taste for seasonings. Use a slotted spoon to transfer the asparagus to a bowl. Let them cool for about 20 minutes. Meanwhile, prepare the balsamella for the stuffing with the 6 tbl. of butter, the flour, milk and salt. (Melt butter over low heat, add flour, stir with wooden spoon constantly for 3 minutes or so and then add hot milk, all at once. Stir until it starts to thicken, add salt, cook over low heat for about 10 minutes.) Transfer balsamella to crockery bowl, pressing a piece of buttered wax paper over sauce to eliminate skin. Let stand until cool. Prepare balsamella for the topping with ingredients and quantities listed following the same directions as above. Transfer this sauce to a second bowl with waxed paper on top. Let cool. Place egg yolks and Parmesan in the bowl with the cooled sauce for stuffing and mix very well until all ingredients are well incorporated. Add cooled asparagus and mix gently. Preheat the oven to 375 F. To stuff cannelloni, place each pasta square on a board and spread about 3 heaping tablespoons of the stuffing along one of the edges. Then roll up, starting at the same edge. Repeat with all cannelloni, then place them in one or two well-buttered baking dishes. Pour the balsamella for topping over the cannelonis, sprinkle with Parmesan cheese, and bake for about 20 minutes or until bubbling. Allow to cool about 10 minutes, then serve.