Preheat oven 400 degrees. Line a baking pan with parchment paper Drizzle the olive oil over the cut side of the squash. Sprinkle with salt and pepper.
Place cut side down on baking sheet. Tuck 3 cloves garlic, 1 tbsp. butter, 1 bay leaf, 1 sprig of rosemary and 1 sprig of thyme under the cavity of each half of squash. Roast in oven for 60 minutes. Set squash aside on cutting board to cool. Discard the rosemary, thyme and bay leaves. Reserve the garlic cloves. Scoop the squash out of the skin. Add the garlic cloves and chop the squash up. Set aside.
Add the remaining butter to large pot. Brown the onions for 10 minutes on med low heat to caramelize. Deglaze with the wine scrapping up the bottom of pan. Let it evaporate. Add the squash mixture to the pan and cook 10 minutes stirring frequently. Add the chicken stock, 1 sprig of thyme, 1 sprig of rosemary, and 1 bay leaf. Bring to a boil. Reduce heat and simmer 15 minutes. Remove the thyme rosemary and bay leaves and discard. Remove pan from heat and puree with immersion blender or food processor until nice and smooth.
Add back to medium heat and stir in the heavy cream , lemon juice and nutmeg. Taste and adjust seasoning for salt. Mix the maple syrup with the creme fraiche. Serve the soup topped with a drizzle of the creme fraiche mixture and garnished with a rosemary sprig.