Heat oven to 400° F. Slice the loaf into 1-inch-thick slices without cutting all the way through the bread.
Melt the butter in a small saucepan over medium heat. Add the garlic and cook, stirring often, until fragrant, 1 to 2 minutes; let cool slightly. Add the parsley and ½ teaspoon salt. Brush the butter mixture between the slices and wrap the loaf in foil.
Bake until warmed through, 10 to 15 minutes. Open the foil and bake until lightly toasted on top, 5 to 7 minutes more. Serve warm.