Throw the spaghetti into boiling, salted water. In a skillet over a medium flame, pour in olive oil and render the pancetta. (Do not brown the pancetta severely.) Add onions and salt them. Allow the onions to sweat down. Deglaze with white wine. Reduce the liquid. Before draining the pasta, remove a cup of the water used to cook the pasta. When drained, toss the pasta into the skillet and enough water (2 Tbl) to create a sauce. Shut off the heat. Pour the beaten egg mixture into the pasta slowly, while stirring vigorously with a spatula. The residual heat will entirely cook the eggs - without scrambling.