1. Bring a large pot of salted water to a boil and cook the spaghetti until al dente. Reserve at least 60 ml (1/4 cup) of the starchy cooking water before draining.

2. While the pasta cooks, heat olive oil in a skillet over medium heat. Add the diced bacon and cook until crisp and golden, about 5–6 minutes. If using garlic, add it during the last minute of cooking and stir until fragrant, then discard the garlic piece.

3. In a mixing bowl, whisk the egg yolk with the grated Parmesan until smooth. Set aside.

4. Return the drained spaghetti to the pot. Immediately add the hot bacon and skillet fat, then pour in the egg and cheese mixture. Toss quickly and vigorously, adding a splash of reserved pasta water to emulsify and coat the strands.

5. Serve immediately with a final grind of black pepper, a sprinkle of extra Parmesan, and fresh basil if desired. Place the empty eggshell on the plate for presentation if preferred.