Add the nuts and use a rubber spatula to mix them into the butter mixture until well coated.
16 ounces mixed nuts
Spread the coated nuts on the parchment-lined baking sheet. Sprinkle them with salt.
¾ teaspoon sea salt
Bake the nuts in the preheated oven until fragrant and browned, for about 25-30 minutes (see the notes section below for tips about adjusting the roasting time).
Remove the pan from the oven. Leave the nuts on the baking sheet and let them cool and crisp up, undisturbed, for about 20 minutes.
When cool, gently separate them with your hands (they tend to stick together), then store them at room temperature in an airtight container for up to a week.
Video
Notes
Seasonings, especially saltiness and sweetness, are just guidelines. Adjust to taste.
I like to use 4 ounces each of hazelnuts, almonds, pecans, and shelled pistachios.
It's important to roast the nuts in a slow oven. 300°F is good. Don't be tempted to increase the oven's temperature - the nuts won't roast as evenly and might even burn.
Oven temperatures vary. If your oven runs hot, the nuts will be ready faster. Start checking after 20 minutes.
You can keep the leftovers in an airtight container at room temperature for up to a week. They lose some crunchiness after the first day but are still delicious. You can reheat them in a 350°F oven for 5-10 minutes to restore their crunch. If you'd like to store them for over a week, place them in an airtight container and keep them in the fridge or freezer.