Preheat oven to 500 degrees F.
Cut potatoes into 1” thick slices, and place the slices in a medium bowl. Pour in the olive oil, melted butter and rosemary. Season with salt and pepper and toss until evenly combined.
Lay the potatoes flat, in a single layer, on a 9”x13” metal baking dish, using two dishes if necessary. (Do not use a glass baking dish, as pouring the chicken broth into the hot pan could resulting in the glass cracking.) Bake until the bottom of each potato is golden brown, about 15 minutes.
Remove the dish from the oven and flip each potato. Bake for another 15 minutes, until the other side of the potato is golden brown.
Remove dish from oven, pour in chicken broth and sprinkle with garlic. Return to oven to bake until the potatoes are tender and the stock reduces slightly, about another 15 minutes.
Serve warm with extra sauce drizzled on top.