There are a few ways to help the spices stick to the nuts.  One way, and the one you'll find most often, is to coat the nuts in oil. While I'm not opposed to using oil, especially for a holiday snack or treat, we don't need the flavor from the oil for this recipe and I don't find the added fat and calories necessary here.   Another common way is to blanch the nuts in boiling water, toss with the spices, and then roast.   For this recipe, pure maple syrup is the answer. They are the glue that will hold the spices on the nuts in addition to bringing delicious sweetness to balance the spices.