Preheat the oven to 375F. For the dressing, toss together the tomato, onion, garlic, 1 tablespoon extra-virgin olive oil, ¼ teaspoon salt, and black pepper in an 8 by 8-inch casserole dish. Cover the dish with foil and roast until the veggies are tender and starting to brown in spots, about 45 minutes; cool slightly.
To make the pepperoni chips, arrange the pepperoni in a single layer on a large baking sheet and bake until crispy, about 8 to 10 minutes at 375F. Transfer the pepperoni to a paper towel-lined plate to drain any excess oil.
Add the roasted veggies, remaining 3 tablespoons extra-virgin olive oil, remaining ¼ teaspoon salt, balsamic vinegar, and water to a blender and process until smooth. Stir in the Italian seasoning.
To serve, arrange the spring mix on 2 plates. Top each with the red bell pepper, red onion, mushrooms, pepperoni chips, and Parmesan cheese. Drizzle some dressing on each and serve immediately.
Notes
Store leftover Creamy Roasted Tomato-Garlic Dressing in the fridge for up to 1 week.
If you don't have time to whip up this dressing, use your favorite store-bought Ranch instead.
Omit the cheese to keep this Pizza Salad recipe paleo!