01 - Preheat the oven to 425°F. Line a large 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 fork-tender.
03 - Place the rinsed and 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 alongside the vegetables for 20 to 25 minutes, shaking the pan occasionally, until the chickpeas are crispy on the outside.
04 - Place the peeled and diced potatoes in a large pot and cover with cold water. Add a generous pinch of salt. Bring to a rolling boil over high heat, then reduce to a simmer. Cook for 15 to 20 minutes until the potatoes yield easily to 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 - In a small saucepan over medium heat, whisk together the olive oil and flour to form a roux. Cook for 1 to 2 minutes, whisking constantly, until the mixture turns lightly golden. Slowly pour in the vegetable broth while whisking vigorously 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, pourable consistency.
06 - Divide the creamy mashed potatoes among four serving bowls. Arrange the roasted vegetables and crispy chickpeas over the potatoes. Drizzle generously with the warm vegan gravy. Garnish with chopped chives, sliced green onions, or crispy fried onions as desired. Serve immediately while warm.