Prep the ingredients as instructed above.
Prepare the Watermelon Mint Drink: Mix watermelon chunks, water, and fresh mint together. Refrigerate until ready to serve. Serve over ice if desired.
Bring a pot of water to a boil. Add salt to season the water. Cook broccoli until tender, then drain well and set aside.
Season chicken with salt and pepper, then drizzle with olive oil.
Heat a grill or grill pan over medium heat. Grill the chicken on both sides until the internal temperature reaches 165°F (74°C). Set aside.
Make the Alfredo Sauce: In a saucepan, melt butter over medium heat. Stir in heavy cream and let reduce until creamy, about 5–8 minutes. Add half of the Parmesan cheese to the cream mixture and whisk until smooth.
Bring another pot of water to a boil and season with salt. Cook the fettuccine pasta according to package instructions. Drain, reserving about ¼ cup of pasta water per serving.
Add the cooked pasta, chicken, and broccoli to the Alfredo sauce. Toss to coat. Garnish with the remaining Parmesan cheese. Add reserved pasta water as needed for a smooth, creamy consistency. Toss with parsley.
Prepare the Tomato and Avocado Side: Portion tomato and avocado slices. Drizzle with olive oil, sprinkle with diced garlic, and season with salt.
Serve the fettuccine with tomato and avocado and watermelon mint drink.