Prepare all ingredients per the instructions above.
Make meat sauce: Heat a pot over medium heat. Add olive oil, garlic, and onion. Sauté until softened. Add ground beef and cook until browned, breaking into small pieces. Stir in crushed tomatoes, season with salt and pepper, partially cover, and simmer on low for 30–35 minutes.
Cook spaghetti: Cook pasta according to package instructions until al dente. Drain, reserving pasta water if desired. Add pasta to meat sauce and stir to coat. Mix in butter and basil.
Cook peas: In a pan over medium heat, melt butter. Add peas and sauté 2–3 minutes until heated through. Season with salt and pepper.
Prepare drink: In a glass or pitcher, combine sparkling water with lemon slices. Serve over ice if desired.
Serve: Plate spaghetti with extra Parmesan. Serve alongside peas, watermelon slices, and lemon sparkling water.