Put an oven rack in the highest position and preheat the brolier to high. Slice the baguette into 20 thin slices.
Place the slices on a baking sheet and broil until golden brown, about 1-2 minutes. Pay careful attention to the bread as it broils so it doesn't burn.
Carefully turn the bread slices and broil the other side about 1 to 1 1/2 more minutes. Set bread aside.
Peel, core and finely chop the pear and place it in a medium sized bowl. Toast the walnuts and then add to the diced pear. Add the cheese and the vinaigrette, then toss to mix. If making ahead, cover and refrigerate for up to 4 hours.
Spoon 1 heaping tablespoon of the topping over each bread slice. Broil for 1 to 2 minutes to melt the cheese. Place the crostini on a serving platter and enjoy!