Toss together pear slices and lemon juice; set aside.
Broil French bread slices 5 inches from heat 1 minute on each side or until lightly toasted.
Stir together cheese and milk until smooth; spread evenly on 1 side of each bread slice. Sprinkle each slice with 1 teaspoon walnuts; top with 1 pear slice and bacon.
Big hit at a party--would definitely make it again. I'm a vegetarian so I omitted the bacon but added a drizzle of honey and it was great.