In a casserole melt the butter and the flour together, cook on low heat while stirring for 5 minutes.
Pour the sauce in a form for making ice cubes and place in the freezer for later.
Take away the skin from the chicken and pour in a casserole. Cut the chicken and the veal in small pieces. Place the chicken and veal pieces in the casserole with the chicken skin.
Peel the carrots, garlic and onion and cut in small pieces and add in the casserole with the meat.
Cut the leek, parsley and the mushrooms and pour in the casserole with the rest of the ingredients. Season with the species and stir together.
Add water so it covers everything in the casserole and let it all simmer on low heat for 1 hour.
Roll out the puff pastry rolls. Cut 4 big circles per bouchée. On two of the circles cut away the middle so you have 2 thine borders.
Place a baking paper on a baking sheet and place one big circle per bouchée as a bottom, then place the 2 thin borders on top per bouchée and place one big circle as a hat on top per bouchée.
Brush the bouchées with the egg yellow and place in the middle of the oven for 20 minutes or until they become golden brown on the surface.
Prepare the pasta according the instructions on the box.
Pour the white wine and the heavy cream in the casserole and cook for 15 more minutes.
Take out the bouchées from the oven and cut of the top the bouchées.
Take out the ice cube sauce from the freezer and mix with the sauce in the casserole.
Place the bouchées on pates and pour sauce in them. Place back the top and pour some extra sauce on the side. Serve together with the pasta.