1/2 cup butter, softened
1 cup packed light brown sugar
1 tablespoon lemon zest
2 teaspoons white sugar
1 egg
1 teaspoon vanilla extract
6 cups all-purpose flour
6 tablespoons milk
1 teaspoon baking powder
3/4 teaspoon salt
1/2 cup chopped peaches
Preheat oven to 350 degrees F (175 degrees C).
In a medium bowl, mix butter, brown sugar, lemon zest, white sugar, egg and vanilla. Make a well in the center of the mixture and pour in flour, milk and baking powder. Mix, then pour mixture into greased 10x15 inch baking pan.
Bake in the preheated oven for about 30 minutes, or until crust is golden brown. Cool substantially before removing from oven.