Step 1: Bring a large pot of salted water to boil and cook spaghetti according to package directions until al dente. Reserve 1/2 cup pasta water before draining.
Step 2: While pasta cooks, heat olive oil in a large skillet over medium-high heat. Season chicken with salt and pepper, then cook until golden and cooked through, about 6-8 minutes. Remove and set aside.
Step 3: In the same skillet, add pancetta and cook until crispy, about 4-5 minutes. Remove pancetta, leaving fat in skillet.
Step 4: Add shrimp to the skillet and cook until pink and opaque, about 2-3 minutes per side. Remove and set aside with chicken.
Step 5: Reduce heat to low. Add minced garlic to skillet and cook for 30 seconds until fragrant.
Step 6: In a medium bowl, whisk together eggs and Parmesan cheese until smooth.
Step 7: Add drained spaghetti to the skillet with garlic. Quickly pour egg mixture over hot pasta, tossing constantly to create a creamy sauce (the residual heat will cook the eggs without scrambling).
Step 8: Add reserved pasta water as needed to reach desired sauce consistency.
Step 9: Return chicken, shrimp, and pancetta to the skillet. Gently toss to combine and heat through.
Step 10: Season with additional salt and pepper if needed. Garnish with fresh parsley and extra Parmesan before serving.