Preheat the oven to 400°F (200°C).
Roast the chickpeas: In a bowl, toss the chickpeas with smoked paprika, garlic powder, olive oil, salt, and pepper. Spread out on a parchment-lined baking sheet in a single layer. Roast for 30–35 minutes, shaking the pan halfway through, until golden and crispy.
Roast the veggies: On a separate large baking tray, toss the cabbage with olive oil, salt, and pepper. Roast for 15 minutes. Then add the kale to the tray and toss everything together. Roast for another 10–12 minutes, until the kale is crisp-tender and the cabbage is caramelized. Lastly sprinkle over the pepitas.
Make the dressing: While the veggies roast, heat a small skillet over medium heat with 1 teaspoon olive oil. Sear the lemon slices for 2 minutes per side until browned. Add to a blender along with garlic, maple syrup, mustard, olive oil, salt, and pepper. Blend until smooth and creamy. Taste and adjust seasoning.
Assemble: In a large bowl, toss the roasted cabbage, kale, and seeds with the lemon dressing. Pile onto plates and top with crispy chickpeas. Serve warm.