Special equipment: A pasta rolling machine, a pastry cutter, a food processor and spray bottle.
For the ravioli: Sift the flour and salt into a mound on a clean work surface. Hollow out a well in the center of the flour. Combine the eggs and olive oil in the hollow.Whisk the eggs with a fork, slowly drawing in some of the flour. Slowly draw in more flour, using your hands until a ball forms. Knead the dough for 10 minutes, adding flour so that the dough is smooth and elastic, not sticky or wet. Place the pasta dough in a lightly oiled bowl and cover with plastic wrap. Let rest for 30 minutes at room temperature.
In a small skillet, over medium heat melt the butter and saute the onions until tender. Combine the onions with the Taleggio, ricotta and Parmesan cheeses. Season, to taste, with salt and pepper.
Roll 1/4 of the pasta through a pasta rolling machine starting at the widest setting and working down to the narrowest setting, rolling the pasta through twice at each setting to work the dough. Lay the rolled pasta flat and trim the edges with a pastry cutter or knife.
Place 1 tablespoon of filling at 2-inch intervals along the length of the pasta, 1/2-inch from the edge. Spritz the pasta with water and fold in 2, lengthwise, over the filling. Press down on the pasta all around the mounds of filling to ensure a good seal. Cut the pasta into squares with the filling in the middle. Repeat with the rest of the pasta and filling. Cover the ravioli and set aside until ready to cook. Any remaining unrolled pasta can be stored, double wrapped, in refrigerator for 3 days or in the freezer for up to 1month.
For the sauce: Preheat the oven to 375 degrees F.
Place the peppers on a baking sheet and bake for 25 minutes. Place the hot peppers in a large bowl and cover with plastic wrap to steam. Peel the peppers and remove the stem and seeds. In a small skillet over medium heat, melt the butter and olive oil and saute the garlic for 15 seconds. Add the anchovies, reduce the heat to low and cook for 1 minute.
In a food processor, puree the roasted peppers, anchovy mixture, lemon juice and salt until smooth. Place in a pot and warm over medium heat.
Bring a large pot of salted water to a boil. Drop the ravioli into the boiling water and cook for 2 minutes. Drain ravioli and toss with warm sauce. Garnish with parsley.