Preheat the oven to 400°F and line a large baking sheet with parchment paper.
Press the extra firm tofu with a clean towel to remove excess moisture, then cut it into 1/2-inch cubes.
In a large mixing bowl, toss the chickpeas, tofu cubes, broccoli, and cauliflower with the olive oil, garlic powder, smoked paprika, sea salt, and black pepper.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the ingredients are not crowded to allow for proper browning.
Roast for 25 to 30 minutes, tossing halfway through, until the vegetables are tender and the tofu is golden and slightly crispy.
Remove from the oven and immediately sprinkle the nutritional yeast over the hot mixture, tossing gently to coat.
Transfer the roasted mixture to a bowl, drizzle with fresh lemon juice, and top with the hemp hearts before serving.