Put a large pot of salted water on the stove; bring to a boil. Meanwhile, heat up a large skillet on the stove and add the olive oil. Cook the bacon until browned and crispy; remove from pan and drain on paper towels. When cool, crumble and set aside.
In a small bowl, mix the beaten egg yolks with the parmesan cheese, stirring well to prevent lumps.
When the water is boiling, put the pasta in the pot and cook for 8 to 10 minutes, until al dente.
Turn the heat down in the skillet to medium low heat, toss the garlic into the hot pan with the oil and bacon fat and saute for less than one minute, to soften. Add the butter.
Now add the hot al dente pasta to the skillet –I use tongs to move the pasta directly from the pasta pot into the skillet. Using the tongs, toss the pasta around for about 2 minutes to coat the strands with the fat in the pan. Add ¼ cup cream.
Remove from heat and pour in the egg/cheese mixture along with some of the reserved pasta water. Stir very quickly until the eggs thicken. Thin out the sauce with more of the reserved pasta water and a bit more cream if necessary to reach desired consistency.
Season the pasta with the black pepper, taste to see if it needs salt. To serve, place the carbonara into serving bowls and garnish with the crumbled bacon, the parsley and more freshly grated cheese. Mangia!