Adjust an oven rack to the middle position and heat the oven to 450 degrees. Toss the carrots, onion, 1 teaspoon of the oil and 1/2 teaspoon salt on a rimmed baking sheet and then spread in an even layer. Roast until the vegetables are well browned and softened, stirring occasionally, 25 to 30 minutes.
Transfer the roasted vegetables to a large saucepan. Add the remaining 1 teaspoon oil,cover,and cook over medium-low heat, stirring often, until the carrots soften further, 3 to 5 minutes. Add the garlic and cook until fragrant, about 30 seconds. Stir in the wine and bay leaf; cook until the wine has reduced by half, about 1 minute. Add the broths. Bring to a boil over medium-high heat; cover, reduce the heat to medium- low and simmer until the soup is flavorful, about 5 minutes.
Puree the mixture in a blender (or food processor) until smooth,and return to a clean saucepan. Add the half-and-half and warm over low heat until hot,about 3 minutes. Season with salt and pepper to taste. (The soup can be refrigerated in an airtight container for up to 4 days. Warm over low heat until hot; do not boil.).