2 eggs worth of fresh pasta (preferably spaghetti-sized)6 slices of bacon (or pancetta, if available)
Trim excess fat from bacon and cook in a frying pan. When the bacon is nearly done, pour off excess grease, add a bit of olive oil, and crush the garlic into the pan. Simmer until the bacon finishes cooking and remove from heat.
In parallel, beat eggs thoroughly in a small dish, adding dashes of cayenne pepper, salt, and black pepper.
Cook pasta al dente. When pasta is done, remove from heat, drain quickly, and return to pan. Drip egg mixture into pasta in small stream, allowing the hot pasta to cook the egg. Keep covered as much as possible to retain heat. Gradually add bacon mixture, parmesan cheese, cayenne pepper, salt, and black pepper to taste, mixing it throughout the pasta. Depending on the size of your eggs, type of pasta, etc. you may need to keep the pan on low heat during this process, to ensure that the eggs get thoroughly cooked, the cheese melts, and the whole mixture is still at a palatable temperature.
I've found that coming up with the proper proportions of ingredients makes a big difference between a bland carbonara and an excellent-tasting one. The quantities above are given as rough guidelines and should be altered to suit one's tastes. Experiment until you find the blend that makes you happiest.