Bring a large pot of water to a boil. Add cabbage leaves and gently boil about 3 minutes. Drain and let cool in a colander.
If using quinoa, cook according to package (approx. 20 minutes).
Heat olive oil in a saucepan. Add onion and saute for a couple minutes. Add the ground beef and stir occasionally until almost cooked. Add garlic, spinach, salt, pepper, and herbs.
Saute a couple more minutes until spinach wilts, then add to a bowl with optional quinoa.
To assemble rolls lay a leaf out flat and place 1/4 to 1/3 cup filling in its centre. Fold in sides and roll up like a tight burrito. Repeat with the remaining leaves and filling.
Spread almost half a cup in the bottom of a casserole dish. Place rolls seam side down and top with remaining sauce.
Bake at 375 F for approximately 30 to 40 minutes, until everything is piping hot. Serve immediately. Alternatively, cook on Low in slow cooker for 6 to 8 hours.