Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper and set aside.
Prepare the parsnips by slicing each one into 6 pieces of similar size (smaller/skinnier parsnips will only need to be cut into 2-4 pieces). Transfer them to the lined baking sheet, and spread them out in an even layer. In a small bowl, whisk together the olive oil, honey, and rosemary. Pour the glaze over the parsnips and use your hands or a rubber spatula to make sure they are coated. Sprinkle generously with sea salt.
Transfer the parsnips to the oven and bake for 30-35 minutes, or until tender. Around 10 minutes before the parsnips are finished (at the 20 or 25-minute mark), take the baking sheet out and sprinkle the raisins on top. Put it back in the oven to finish cooking.
When they're finished, transfer to a serving dish, garnish with additional rosemary or sea salt, and enjoy warm.
You can make this up to 2 days in advance. Store in an airtight container in the fridge. Reheat in a preheated oven (350-400 degrees F) on a lined baking sheet until warm, about 10 minutes.