Preheat oven to 350°. Spread nuts in a rimmed baking sheet and roast until golden in center, about 15 minutes (break one open to check). On a work surface, wrap nuts in a kitchen towel and rub vigorously to remove loose skins. Transfer nuts to a bowl. Line baking sheet with parchment paper and set aside.
Combine rosemary, paprika, salt, and pepper in a small bowl; set aside.
Melt butter in a 12-in. frying pan over medium heat. Add sugar and 1/4 cup water. Cook, stirring constantly and scraping down inside of pan, until mixture turns light golden and a haze starts to form (sugar will melt, then clump up, then melt again), 8 to 10 minutes.
Add nuts; stir and turn them constantly with a spoon and spatula until syrup and nuts are deep golden brown, 2 to 3 minutes. Working quickly, remove pan from heat, add salt mixture, and stir until nuts are evenly coated, breaking up clumps.
Carefully spread hot nuts on lined baking sheet in a fairly even layer. Let cool about 15 minutes, then break apart and cool completely.
Make ahead: Up to 1 week, stored airtight.