2) In a blender, combine the sage, pine nuts, olive oil, garlic, Parmesan, 1/2 teaspoon salt and 1/4 teaspoon black pepper. Puree until smooth.
3) Season the turkey all over with salt and black pepper and transfer to the prepared pan. Spread pesto all over the top of the turkey. Arrange potatoes around the pan, spray with cooking spray and season with salt and freshly ground black pepper.
4) Roast for 30 minutes, until the potatoes are golden brown and the turkey reaches 70C. Let the turkey rest for 10 minutes before slicing crosswise into 1.25cm-thick slices.