Put 1 tablespoon of the roasted pear puree into a Champagne flute and add pear nectar 1/4 way up the glass. Top off with Champagne. Repeat with remaining drinks. Serve immediately.
Preheat the oven to 375 degrees F. Put 2 pieces of foil on a flat surface and place 1 pear in the center of each. Drizzle both with the honey and loosely wrap them in the foil, leaving the top open. Place the pears in the top half of the oven and roast until they are buttery soft, about 50 to 60 minutes. Remove from the oven and let cool. Peel the skin off with your hands and pull the flesh away from the core. Place in a blender with any accumulated juices and puree until smooth. Pour into a container and refrigerate until ready to use.