Heat oven to 375 degrees F. Lightly butter 2-quart casserole. Pour broth into 2-quart saucepan. Add potatoes; stir in 1 teaspoon salt. Heat to boiling. Reduce heat; cover and simmer about 10 minutes, stirring occasionally, until potatoes are tender. Place colander over medium bowl; drain potatoes, reserving broth.
Rinse and dry saucepan. Cook 2 tablespoons of the butter and the garlic in saucepan over low heat 2 minutes, stirring occasionally.
Return potatoes to saucepan with butter and garlic; mash with potato masher.
Add 1 cup of the reserved broth to potatoes; mix until smooth. Stir in remaining 2 tablespoons butter and 1/4 cup of the cheese. Adjust seasoning to taste with salt and pepper.
Spoon potato mixture into casserole. Top with remaining 1/4 cup cheese and the bread crumbs. Bake about 20 minutes or until golden brown.