In large bowl, beat cream cheese and 1/4 cup sugar with electric mixer on medium speed until well blended. On low, beat in egg just until blended. Add lemon peel and lemon juice; beat until smooth. Spoon about 1 teaspoon cream cheese mixture over crumb mixture in each cup. Place 5 to 6 of the white baking chips on top of each (using 1/4 cup total). Divide remaining cream cheese mixture evenly among cups (about 2 heaping teaspoons each).