Start by preheating your oven to 380F and line a sheet pan with parchment paper.
Place the peeled and cubed sweet potatoes, carrots, onion on the sheet pan. Cut the tops off from the garlic bulbs, just to expose the cloves. Drizzle everything with olive oil and bake in the oven for 40 minutes.
Heat up a 4-quart Dutch oven or soup pot, on medium heat. Melt the butter in the pan and then add in the grated ginger. Cook for a minute, just to release all of the flavors.
Deglaze the pot with the vegetable broth. Squeeze the roasted garlic bulbs into the pot to release the cloves and add in the roasted vegetables. Simmer for 15-20 minutes.
Blend the soup until smooth and adjust seasoning as needed. Stir in the chopped fresh dill and the optional half & half.