SEASON meat with salt and pepper. Heat oil in a large pot or Dutch oven over medium-high heat. Add meat; cook, stirring occasionally, for 5 minutes or until browned. Remove from pot. Add chopped cauliflower stems, onion and garlic to pot; cook for 5 minutes. Stir in harissa, tomato paste, cumin and coriander; cook for 1 minute. Stir in broth; return beef to pot. Bring mixture to a boil. Reduce heat to medium-low; cover. Cook for 1 to 1 1/2 hours or until meat is tender.
STIR in cauliflower florets and chickpeas. Cook for 15 to 20 minutes or until cauliflower is tender. Add salt and pepper, if desired.
WHILE cauliflower and chickpeas are cooking, prepare pasta according to package directions. Drain; spread on a serving platter. Top with stew. Serve with additional harissa, if desired.