Prepare. Preheat your oven to 350 and line a rimmed baking sheet with foil, a baking mat, or parchment paper.
Large Nuts. Evenly scatter your larger nuts (such as walnuts) over your prepared baking sheets. Bake these nuts for five minutes to get them warm and slightly crisp.
Combine. Meanwhile, while your larger nuts are baking, places the remaining nuts and optional seeds in a large bowl. In a smaller bowl, use a whisk to combine together the oil, seasonings, and two tablespoons of the rosemary. Pour half of this over the nuts, toss, and repeat with the remaining.
Warm nuts. Carefully add the oven warmed nuts to the large bowl and toss the ingredients, using two large spoons or similar items, until the ingredients are fully combined.
Bake. Evenly spread the coated nuts over the rimmed baking sheet and return the sheet to your oven. Bake the nuts for five minutes and then carefully stir the ingredients. Continue to bake for another five to six minutes or until the nuts are 'fragrant' and beginning to brown.
Serve. Allow the nuts to fully cool on this pant at room temperature before serving or storing.