1. Bring a large pot of salted water to a boil and cook the fettuccine according to package instructions until al dente. Reserve 1 cup of pasta water, then drain and set aside.
2. In a large skillet over medium heat, melt 2 tablespoons of butter. Add the broccoli florets and sauté for about 4-5 minutes until they are vibrant green and tender. Remove from the skillet and set aside.
3. In the same skillet, melt the remaining butter and add the shrimp. Season with salt and pepper. Cook for 2-3 minutes on each side until the shrimp are pink and opaque. Remove from the skillet and set aside.
4. Add minced garlic to the skillet and sauté for about 30 seconds, until fragrant. Pour in the heavy cream and bring to a gentle simmer, stirring occasionally.
5. Gradually whisk in the Parmesan cheese until the sauce is smooth and creamy. If the sauce is too thick, add some of the reserved pasta water, a little at a time, until you reach your desired consistency.
6. Add the cooked fettuccine, broccoli, and shrimp back into the skillet. Toss everything together until well coated with the sauce. Sprinkle with lemon zest and adjust seasoning with salt and pepper if needed.
7. Garnish with fresh parsley before serving. Enjoy your homemade shrimp broccoli alfredo!

Remember, patience is key when making alfredo sauce. Stir gently, and allow the flavors to meld together beautifully. This is where cooking becomes a meditative process, reminiscent of those childhood days spent in the kitchen with my abuela.