On large rimmed baking sheet, toss broccoli with 1 tbsp of oil, broth or water, & half of each of the garlic, cumin, salt & pepper.
Then spread out into even layer & roast for 10 minutes
In large bowl, combine chicken, 1-1/4 tsp freshly grated lemon zest, remaining oil, garlic, salt, pepper & pinch of cayenne
Remove baking sheet from oven & add chicken, toss together with broccoli.
Return sheet to oven & roast, tossing once halfway through cooking time, until chicken is cooked through & broccoli is tender and golden around edges, about 8-10 minutes
Serve with lemon wedges or squeeze lemon juice all over just before serving