Preheat the oven to 400°F.
Cut the red bell pepper, zucchini, and red onion into bite-sized pieces. Toss the vegetables with olive oil, a pinch of salt, and black pepper, then spread them out on a baking sheet.
Roast the vegetables in the oven for 20-25 minutes until tender and slightly charred.
While the vegetables roast, cut the chicken breast into cubes. In a bowl, mix the Greek yogurt, tomato sauce, garlic, ginger, garam masala, turmeric, cumin, coriander, chili powder, and a pinch of salt. Add the chicken pieces and coat them thoroughly with the marinade.
Heat a non-stick pan over medium heat and add the marinated chicken along with any extra marinade. Cook the chicken for about 8-10 minutes, stirring occasionally, until the chicken is cooked through and the sauce thickens.
Plate the creamy chicken tikka masala and serve it alongside the roasted vegetables. Enjoy your nutritious, flavorful meal!