1. Preheat the oven to 425 degrees F.
2. Place the sweet potato on a baking sheet and bake until soft, 35 to 40 minutes. Allow to cool, then peel it.
3. Meanwhile, heat a large deep skillet over medium-high heat. Add the olive oil and heat until just hot. Add the carrots, celery, onion and salt. Cook, stirring occasionally, until the onions just turn translucent, about 5 minutes. Add the garlic, thyme and bay leaf and cook, stirring occasionally, until the vegetables are nice and brown, 5 to 7 minutes.
4. Stir in the tomatoes with their juices and cayenne, then stir in the broth. Bring to a boil, then reduce the heat to maintain a steady simmer until the carrots are tender, about 15 minutes. Remove and discard the thyme sprigs and bay leaf. Add the roasted sweet potato.
5. Using a blender, puree the soup until silky smooth. Return the soup to the skillet and heat on low. Stir in the cream. For a thinner soup, stir in more broth. Season to taste and serve hot with the micro basil and Croutons.

Pesto Grilled Cheese Croutons:

1. To the bowl of a food processor, add the basil, garlic, pine nuts, Parmesan, lemon zest and salt. Pulse until the mixture forms a chunky paste, scraping down the sides and bottom of the bowl occasionally. With the machine running, add the olive oil in a steady stream. Keep processing until the desired consistency is reached, pulsing less for a more coarse pesto and more for a smooth one. Season to taste.
2. To make the sandwiches: Spread some pesto on 1 side of 2 slices of bread. Arrange a slice of Cheddar over the pesto on 1 slice of bread. Sandwich with the other slice of the bread, pesto-side down. Repeat with remaining pesto, bread and Cheddar.
3. Mix the butter and mayo together in a small bowl. Spread a generous layer on both sides of each sandwich.
4. Place the sandwich in a nonstick skillet and turn the heat to medium-low. Cook, turning occasionally, until the bread is nice and toasty and golden brown, the cheese is melty and the sandwich is heated through. Repeat with the remaining sandwiches. Cut into croutons.