Up to 1 hour ahead of time, core and chop three pears into small pieces; toss with 1 tablespoon lemon juice. Cut remaining pears into very thin slices or slivers; brush with remaining lemon juice. In large bowl, stir together cheese and milk. Stir in 1/2 cup of walnuts and bacon; fold in chopped pears. Cover and chill up to 2 hours. Wrap and store pear wedges separately.
To serve, place rounded tablespoon of cheese mixture on each toast. Top with pear slice or wedge. Finely chop remaining nuts and sprinkle atop. Makes 24.