Peel the parsnips and potatoes and grate them into a bowl. Finely slice the Brussels sprouts and add to the bowl. Crack the egg into this mixture and combine. Then, add the garlic and rosemary.
Next, use your hands to shape the mixture into four rösti patties of the same size. Slice the cooked turkey breast.
Put the turkey into a pan over a low heat and warm through.
Heat the olive oil in a separate pan and add the röstis. Cook the röstis until golden brown (3 minutes each side).
To serve, put the röstis on a plate, layer the turkey slices and add some cranberry sauce on top.