Preheat oven to 350F/ 180C and line a baking sheet with aluminum foil lightly coated with olive oil.
In a bowl toss the pumpkin seeds with the oil, brown sugar, sea salt, & rosemary. Then spread in an even layer onto the foil-lined pan.
Bake for 15 minutes, then gently re-toss & spread. Lower the oven to 300F/150C and continue to bake about 30-45 minutes more until golden brown and slightly caramelized in parts. Season with more sea salt if necessary.
*Make sure the pumpkin seeds are dried before tossing with the other ingredients. (If time allows, you can spread the rinsed seeds on a baking sheet and put in a cool oven overnight to dry.)
*Roasted seeds will keep in an air-tight container up to a week.