Heat oven to 350°F.

Combine butter and brown sugar in large bowl. Beat at medium speed until creamy. Add banana, avocado, egg, lemon zest and vanilla; continue beating until well mixed. Add flour, baking powder, baking soda and salt; beat at low speed until well mixed.

Using a wooden spoon, gently fold in white chocolate chips.

Drop dough by rounded teaspoonfuls, 2 inches apart, onto ungreased cookie sheets. Bake 10-12 minutes or until edges are lightly browned. Cool completely.