1) Preheat the oven to 190C/Gas 5.
2) Halve the potatoes lengthwise and cut them into 2 1/2-cm-wide wedges. In a medium bowl, toss the potatoes with the butter and salt. Spread the potatoes out on a roasting tray large enough to hold them in a single layer. Arrange them cut-side down, to ensure crisply browned edges.
3) Roast the potatoes until golden brown, about 45 minutes. Add the garlic and stir to coat the potatoes evenly. Continue to roast until the potatoes and garlic are evenly browned, about 15 minutes more. Take care that the garlic doesn't burn. Remove the potatoes from the oven and mix with the parsley.
Season with salt and pepper to taste and serve.