Preheat your oven to 375°F (190°C). Lightly grease a medium-sized casserole dish with non-stick cooking spray.
Steam the broccoli florets for 3-4 minutes until slightly tender but still firm. Set aside.
In a large skillet, heat olive oil over medium heat. Add the diced onion and minced garlic. Sauté until fragrant and golden, about 3 minutes.
Add the zucchini, red bell pepper, and halved tomatoes to the skillet. Sauté for another 4-5 minutes until the vegetables soften slightly.
Toss in the steamed broccoli and baby kale. Stir gently to combine.
Sprinkle the dried oregano, dried basil, smoked paprika (if using), salt, and pepper over the vegetables. Stir to ensure the seasoning is evenly distributed.
Transfer the vegetable mixture into the prepared casserole dish. Spread it out evenly.
Sprinkle the shredded mozzarella cheese evenly on top. Finish with a dusting of Parmesan cheese.
Place the casserole dish in the preheated oven. Bake for 15-20 minutes or until the cheese is melted and bubbly with a golden crust.
Remove the casserole from the oven and let it cool slightly before serving. Garnish with a few fresh basil leaves for an extra touch of flavor and color.