Preheat oven to 425°F. Halve the carrots lengthwise and toss them with the olive oil, salt, and pepper.
Lay the carrots in a lightly greased 12-inch cast iron skillet in a single layer.
In a separate pan, on medium-low heat, melt the butter, then stir in garlic, honey, and brown sugar. Stir constantly for 1 minute.
Drizzle the sauce over the carrots and transfer to the oven to bake for 25 minutes.
Carefully remove the skillet from the oven with a hot pad and let it cool slightly. Top with fresh parsley if you are using it and serve!
Notes
Aim to cut your carrots to a uniform size so they roast evenly. Otherwise, some will be overcooked while others still have a crunch.
Be careful to keep the heat on medium-low when making the glaze. Butter and garlic both burn very easily, which adds a bitter flavor to the dish.
Keep the carrots spaced in an even layer so they roast rather than steam. If you make a double batch, I recommend two skillets or a large sheet pan.
Leftovers can be stored in an airtight container in the fridge for up to 5 days. Reheat them in the oven or on the stove for the best texture.
If you have particularly small or large carrots, the roast time will differ from the recipe. I recommend checking periodically — when they are fork-tender with golden, caramelized edges, they're done roasting.