Prep the ingredients per the instructions above.
Make watermelon mint drink: Blend watermelon, water, and fresh mint. Refrigerate until ready to serve. Pour over ice.
Cook broccoli: Bring a pot of salted water to a boil. Cook broccoli until tender, then drain and set aside.
Cook chicken: Season chicken with salt and pepper; drizzle with olive oil. Grill over medium heat until cooked through to an internal temperature of 165°F (74°C). Set aside.
Make Alfredo sauce: In a saucepan, melt butter over medium heat. Add garlic and sauté 1–2 minutes. Stir in heavy cream and reduce until creamy, 5–8 minutes. Add half the Parmesan and whisk until smooth.
Cook pasta: Boil salted water. Cook fettuccine according to package instructions. Drain, reserving 1/2 cup pasta water.
Assemble Alfredo: Add pasta, chicken, and broccoli to the sauce. Toss well. Add reserved pasta water as needed for creaminess. Garnish with remaining Parmesan and parsley.
Prepare side: Arrange tomato and avocado slices on a plate. Drizzle with olive oil, sprinkle with garlic, and season with salt.
Serve: Plate fettuccine Alfredo with tomato and avocado side. Enjoy with watermelon mint drink.