Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into half-inch cubes, then rinse and thoroughly pat the chickpeas dry with a towel.
On the baking sheet, toss the sweet potato cubes and chickpeas with olive oil, sea salt, black pepper, and garlic powder until evenly coated.
Spread the mixture in a single layer and roast for 25-30 minutes, tossing halfway through, until the potatoes are tender and chickpeas are slightly crispy.
While the vegetables roast, season the chicken breast with a pinch of salt and pepper, then grill over medium-high heat for 6-7 minutes per side until the internal temperature reaches 165°F.
Remove the chicken from the heat, let it rest for 5 minutes, and then slice into thin strips.
In a small ramekin, whisk together the tahini and lemon juice, adding a teaspoon of warm water at a time until a smooth, pourable consistency is reached.
Assemble the bowl by placing the baby spinach at the base, topping with the roasted sweet potato and chickpea mixture and the grilled chicken, then finishing with the lemon-tahini drizzle.