Chocolate Chip Zucchini Bars

I got the zucchini in our CSA share again so it was time to revamp the recipe I tried a few weeks ago.  The taste was there but it seemed oily.  I substituted in plain yogurt for the oil and the bars came out much lighter but just as tasty.  

Chocolate Chip Zucchini Bars

1/2 cup butter, softened
1/2 cup brown sugar
1/2 cup sugar
1/3 cup plain yogurt
1 large egg
1 1/4 cups flour
1 tsp baking powder
1/2 tsp baking soda
1/2 tsp salt
1 tsp vanilla
1 cup shredded zucchini, drained
3/4 cup dark chocolate chips (or semi-sweet)

Cream butter and sugars together.  Beat in yogurt, egg and vanilla.  Slowly beat in dry ingredients.  Hand fold in zucchini and dark chocolate chips.  Put dough in a greased 9 x 9 pan.  Bake for 45 minutes at 325°.