Step 1Bring broth to a boil, then decrease heat so it simmers and stays hot.
Step 2Heat oil in 3-quart saucepan over medium heat. Add barley. Cook, stirring often, until golden, about 5 minutes. Add shallots and garlic. Cook until just starting to soften, about 2 minutes.
Step 3Add 1/2 cup broth. Simmer, uncovered, stirring often with wooden spoon, until most--but not all--of broth is absorbed. Continue adding 1/2 cup broth and cooking in this manner until barley is tender, about 20 minutes total. Toward end of cooking, add the last broth cautiously to avoid having excess liquid when barley is done. Risotto should be creamy but not runny. (Can be made ahead and refrigerated. Gently reheat over low heat until hot, stirring constantly and adding hot broth or water as needed.)
Step 4To serve, stir broccoli and butter into hot risotto; cover and set aside until broccoli is just starting to get tender, about 2 minutes. Taste and adjust seasoning with salt and pepper. Serve hot.