Combine lamb, cauliflower rice, onion, garlic, herbs, olive oil, lemon zest, allspice, and cinnamon. Mix and season.
Lay a grape leaf flat, vein-side up. Place 1 heaping Tbsp of filling near the stem. Fold the bottom up, fold in sides, roll tightly.
Line pot bottom with extra grape leaves. Pack dolmades tightly seam-side down.
Mix lemon juice and broth; pour over dolmades until just covered. Place a heavy plate on top.
Bring to a simmer, cover, and cook on low 45 minutes. Rest 10 minutes before serving.