Bring your cast iron skillet to medium-high heat with the tablespoon of olive oil and whole or minced garlic. Once heated, add cut carrots and turn to coat all sides. Allow to cook for about 5 - 7 minutes without stirring, allowing sides to brown.
Add the butter and brown sugar, stir to combine the brown sugar throughout the melted butter.
Cook for about 4 minutes, stirring occasionally while your glaze sauce forms.
Remove from heat, transfer to your serving dish and sprinkle with parsley (optional garnish).
If you choose to decrease or increase the serving size, the carrots should have approximately the same cooking time so long as they are not piled in many layers in your skillet.