Prepare the ingredients as instructed.
Bring the water to a boil. Remove from heat, add the rooibos tea bags, and steep for 10 minutes. Refrigerate to cool until chilled.
Preheat a grill or grill pan to medium heat, about 400°F (204°C). Grill the chicken on both sides until the internal temperature reaches 160°F (71°C). Remove from heat, rest briefly, then dice into bite-size pieces.
Bring a pot of salted water to a boil and cook the penne pasta according to package directions. Drain well and set aside.
Heat the olive oil in a skillet over medium heat. Sauté the garlic and red onion until onion is softened and translucent.
Add the grape tomatoes and cook briefly until slightly softened. Stir in the chicken broth and heavy cream and bring to a gentle simmer. Cook until the sauce slightly thickens.
Stir in the Parmesan cheese. Add the diced chicken and baby spinach and cook until the spinach is wilted. Season with salt and black pepper.
Add the cooked penne to the skillet and toss until evenly coated in the sauce.
Heat the oil in a nonstick pan over medium heat. Sauté the peas for 2 - 3 minutes. Season with salt and black pepper.
Serve the Tuscan grilled chicken pasta with sautéed peas and rooibos iced tea.