1. Preheat your oven to 400 F (200 C). Line a large baking sheet with parchment paper for easy cleanup.

2. Peel the sweet onions and cut them into 1-inch thick wedges. Try to keep the wedges roughly the same size so they cook evenly. Separate the layers slightly as you place them on the baking sheet.

3. In a small bowl, combine the melted butter and honey. Whisk them together until they are well combined and smooth.

4. Arrange the onion wedges in a single layer on the prepared baking sheet. Drizzle the honey butter mixture evenly over all the onions. Sprinkle the fresh thyme leaves, sea salt, and black pepper over the top. Use your hands to gently toss the onions, ensuring they are all coated with the mixture.

5. Place the baking sheet in the preheated oven. Roast for 25 to 30 minutes, or until the onions are tender and slightly caramelized around the edges. They should turn a beautiful golden-brown color and become soft when pierced with a fork.

6. Once cooked, remove the sheet pan from the oven. Serve them warm as a delightful side dish or as part of your main meal.