Preheat oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Toss sweet potatoes with 2 tsp olive oil, garlic powder, smoked paprika, and black pepper; spread in an even layer.
Roast sweet potatoes 25–30 minutes, stirring halfway, until tender and lightly caramelized.
While potatoes roast, cook quinoa: combine quinoa and 2 cups water in a saucepan, bring to a boil, reduce to low, cover, and simmer 15 minutes; rest 5 minutes, then fluff.
Make the dressing: whisk tahini, lemon juice, 2 Tbsp water, honey, and salt until smooth; add more water if needed to reach a pourable consistency.
Assemble 4 meal-prep containers: divide quinoa, roasted sweet potatoes, chickpeas, spinach, and carrots among them.
Drizzle with lemon-tahini dressing and top with toasted pepitas; seal and refrigerate up to 4–5 days.