Place potatoes and garlic in 4- to 5-quart slow cooker. Place beef on potatoes. Sprinkle dry soup mix over beef; pour beefy mushroom soup over all.
Cover and cook on low heat setting 8 to 9 hours.
Remove beef from cooker; place on cutting board. Cut beef into slices; place on serving platter with potatoes and garlic. Cover to keep warm.
Meanwhile, place frozen broccoli in slow cooker with remaining sauce. Increase heat setting to high. Cover and cook about 15 minutes or until broccoli is tender. Serve with beef and potatoes.