Preheat the Oven
Preheat the oven to 375°F (190°C).
Prepare the Onions
Peel the onions and slice them into thick rounds (about 1/2-inch thick).
Arrange the onion slices in a single layer in an oven-safe baking dish or on a baking sheet.
Make the Butter Garlic Mixture
In a small bowl, combine the melted butter, minced garlic, dried thyme, and dried oregano. Stir well to combine.
Season with salt and pepper to taste.
Drizzle the Butter Mixture
Drizzle the butter garlic mixture evenly over the onion slices, making sure each slice is coated.
Bake the Onions
Cover the baking dish with aluminum foil and bake for 25-30 minutes.
After 25-30 minutes, remove the foil and bake for an additional 10-15 minutes, or until the onions are golden and tender.
Serve
Once the onions are cooked through and caramelized, remove them from the oven.
Garnish with freshly chopped parsley, if desired, and serve immediately.