Whisk eggs, grated cheese, and black pepper in a large bowl until completely smooth. This creamy base will coat every strand of pasta beautifully. The mixture should look pale yellow and luxurious.

Bring a large pot of salted water to a rolling boil. Add spaghetti and cook until just shy of al dente, about 1 minute less than package directions. Reserve 1 cup of starchy pasta water before draining.

While pasta cooks, heat a large skillet over medium heat. Add diced guanciale and cook until crispy and golden, about 5-7 minutes. Add minced garlic during the last minute, letting it become fragrant but not brown.

Remove the skillet from heat. Add the hot, drained pasta directly to the pan with the crispy meat. Toss quickly to coat with the rendered fat.

Slowly pour the egg mixture over the hot pasta while tossing vigorously with tongs. The residual heat will gently cook the eggs, creating a silky sauce. Add pasta water gradually until you achieve a glossy, cream-like consistency that clings to each strand.