Preheat the oven to 350 degrees F.
Combine the mixed nuts in a large mixing bowl.
In a smaller bowl, melt your oil or butter of choice. Stir in maple syrup and rosemary. Pour the mixture over the nuts, stirring as you go to evenly coat them.
Sprinkle the brown sugar, salt, and optional chili powder over the bowl of glazed nuts. Stir and toss to evenly coat the nuts.
Spread the coated mixed nuts out evenly on either a greased (e.g. olive oil) or parchment-paper covered baking sheet.
Bake the nuts for approximately 20 minutes - until they become toasty and golden brown. Stir and toss the nuts twice during baking to ensure even roasting. *Note that the nuts will not seem super crunchy until they’ve cooled. Avoid burning!
Once they’re finished baking, set the roasted mixed nuts out at room temperature and continue to toss and stir periodically to prevent them from sticking together (or to the pan) while cooling. During this time, taste-test the roasted nuts and add more salt if desired.
Serve warm or cool and enjoy!
Store fully-cooled nuts in an air-tight container.