Prepare the oven: Preheat to 375°F (190°C). Grease a baking dish with butter or oil.
Cook the vegetables: In a skillet, heat olive oil and sauté onion and garlic until fragrant. Add broccoli and kale, cooking until just softened (about 4 minutes). Season with salt, pepper, and Italian seasoning.
Make the creamy base: In a bowl, whisk together sour cream (or Greek yogurt), milk, and half of the mozzarella and Parmesan cheese. Stir until smooth.
Combine: In the baking dish, mix the sautéed vegetables with the creamy sauce. Add the tomatoes and stir gently.
Top and bake: Sprinkle the remaining cheese over the top. Add breadcrumbs if using. Bake uncovered for 25–30 minutes, until golden and bubbly.
Serving and Storage Tips
