In a large pot of salted water, cook the pasta according to the package directions.
Meanwhile, in a large skillet, cook the bacon until crisp. Transfer to a bowl and pour off the excess bacon fat.
Add the butter to the pan and cook until it melts and then starts turning golden.
In a small bowl, beat the eggs lightly with a fork, and stir in the grated Parmesan.
Transfer the pasta with tongs, so that you get a bit of the starchy water, to the skillet.
Turn off the heat and add the egg-cheese mixture to the pasta; toss to combine, allowing the heat of the pasta to cook the sauce, adding a bit more of the starchy water if you’d like it saucier.
Return the bacon to the pasta, add a good grinding of pepper, and serve with extra Parmesan grated on top.