In a small saucepan, melt the butter over low heat. Add the minced garlic and cook for about 1 minute, stirring constantly until fragrant. Remove from heat and stir in the chopped rosemary, sea salt, black pepper, and lemon zest.
In a large mixing bowl, combine the halved radishes. Pour the garlic butter mixture over the radishes and toss until they are evenly coated.
Spread the radishes in a single layer on a baking sheet lined with parchment paper.
Roast in the preheated oven for 20-25 minutes, or until they are tender and lightly browned, stirring halfway through for even cooking.
Remove the radishes from the oven and let them cool for a couple of minutes.
Transfer to a serving dish and garnish with fresh parsley before serving.
Notes
For added flavor, try using different herbs or spices.