01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper and set aside.
02 - Toss the cauliflower florets, broccoli florets, and sliced carrot with olive oil, paprika, dried thyme, salt, and pepper until evenly coated. Spread in a single layer on the prepared baking sheet. Roast for 25 to 30 minutes, stirring halfway through, until the vegetables are golden and tender.
03 - Place the drained chickpeas on a separate small baking tray. Drizzle with olive oil and sprinkle with smoked paprika, ground cumin, salt, and pepper. Toss to coat evenly. Bake in the oven alongside the vegetables for 20 to 25 minutes, shaking the pan occasionally, until the chickpeas are crispy on the outside.
04 - Place the diced potatoes in a large pot and cover with cold water. Add a generous pinch of salt. Bring to a boil over high heat, then reduce to a simmer and cook for 15 to 20 minutes, or until the potatoes are easily pierced with a fork. Drain thoroughly and return to the pot. Add the plant-based milk, vegan butter, garlic powder, salt, and pepper. Mash until smooth and creamy.
05 - Heat olive oil in a small saucepan over medium heat. Whisk in the flour to form a roux and cook for 1 to 2 minutes, stirring constantly, until lightly golden. Slowly pour in the vegetable broth while whisking continuously to prevent lumps. Stir in the soy sauce, nutritional yeast, onion powder, salt, and pepper. Simmer for about 5 minutes, whisking frequently, until the gravy thickens to a smooth consistency.
06 - Divide the creamy mashed potatoes among four serving bowls. Arrange the roasted vegetables and seasoned chickpeas on top. Drizzle generously with the vegan gravy. Garnish with chopped chives or parsley, sliced green onions, or crispy fried onions if desired. Serve immediately while warm.