Set your oven to broil on high, with the top rack about 6 inches down from the top burner.
Using an ovenproof skillet over medium/high heat, melt your butter or margarine, then add the onions and garlic and cook until translucent and lightly caramelized, about 5 minutes.
Turn off heat and add the pears, lemon juice, cinnamon, and maple syrup, and toss to coat. Then place the skillet in your oven and broil for about 10 minutes until pears are lightly browned.
Remove from the oven and carefully transfer your soup to a blender. Add the milk and puree until smooth and creamy. Pour your pear soup into bowls and let stand at room temperature for about 20 minutes before eating, or place in the freezer for about 5 minutes and then serve.
I've tried the soup both hot and cold, and the flavours really come out once slightly cooled. You may also enjoy warm, but I prefer this soup served cold.