Place cookies in a food processor; process until crumbly.
Add margarine and egg white, and pulse 5 times or just until moist. Press the crumb mixture evenly into a 9-inch pie plate coated with cooking spray.
Bake at 350 for 8 minutes, and cool on a wire rack 15 minutes. Freeze piecrust 30 minutes.
Place an extra-large bowl in freezer.
Remove yogurt from freezer, and let stand at room temperature while crust is cooling.
Wipe out food processor bowl with a paper towel; add peaches, sugar, and lemon juice. Process until smooth. Spoon yogurt into chilled extra-large bowl. Fold in peach mixture until well-blended; freeze 30 minutes or just until set but not solid.
Spoon yogurt mixture into prepared crust; freeze until set. Cover with plastic wrap; freeze 6 hours or until firm.
Place the pie in refrigerator 30 minutes before serving to soften.