Right before the cooking time for the carrots is up place 6 Tablespoons of butter into a medium sauce pan. Heat the butter until it's melted. Cook and stir the melted butter until it's golden brown. Watch carefully, butter can go from browned to burnt quickly. Place the carrots and onion on a serving platter and pour the browned butter over the roasted carrots and onions. If you're watching your fat intake, the amounts of butter and olive oil in the recipe can certainly be cut back without, in my opinion, hurting the end results.