Sweet Potato Bisque

2 medium sweet potatoes1 yellow onion, peeled and cut in matchsticks2 teaspoons olive oil3 cloves garlic, peeled and chopped2 sprigs fresh thyme2 sprigs fresh rosemary2 bay leaves10 black peppercorns 1/2 teaspoon ground cinnamon 1/4 teaspoon ground nutmeg 1/4 teaspoon ground ginger 1/4 teaspoon ground cloves 1/2 cup madeira wine 1/2 cup maple syrup2 1/2 cups whipping cream, dividedChicken stock, vegetable stock or water as needed2 tablespoons stone-ground mustardSalt and pepper to tasteMatchstick-cut apples and/or nuts for garnishHeat oven to 400 degrees.Roast both sweet potatoes in oven until very tender, 45-60 minutes.While the potatoes are roasting, cook the onion in the olive oil in a stockpot over very low heat until browned and caramelized, about 15 minutes.Make the thyme, rosemary, bay leaves and black pepper into a sachet in a teaball or a piece of cheesecloth. Add to the onions with the garlic and ground spices, stir over medium heat until the spices are fragrant. Increase the heat and add the madeira; bring to a boil, stirring and scraping the browned bits from the bottom of the pot.Reduce the heat and simmer until the mixture cooks down to a syrup. Add the maple syrup. Remove from the heat.Peel and mash the cooked sweet potatoes and add to the stockpot with 2 cups cream. Thin with a little stock or water to a soupy consistency and let simmer over medium heat for 1 hour.Meanwhile, combine the remaining 1/2 cup cream with the mustard in a small saucepan. Simmer over low heat until reduced by 1/2. Remove from the heat and set aside.Remove the soup from the heat and puree until smooth with an immersion blender or in a regular blender in small batches (be careful - the liquid is very hot).Strain through a fine mesh sieve and adjust the consistency with stock or water. Season with salt and pepper. Serve drizzled with a little mustard cream and garnish as desired.Serves four.Chef Greg Darrah, Sage Grille, Highwood