1/2 cup butter
6 (1 ounce) squares white chocolate
2 eggs
2/3 cup granulated sugar
2 teaspoons grated orange peel or 1 teaspoon vanilla extract
1 1/2 cups all-purpose flour
1/2 teaspoon baking powder
1/2 cup semisweet chocolate chips

Melt butter; set aside. Melt white chocolate according to package directions; set aside.

In a large mixing bowl, beat eggs by hand until foamy. Stir in sugar and orange peel. Add melted butter and melted white chocolate. Sift flour with baking powder. Blend flour mixture into egg mixture. Stir in chocolate chips. Spread batter evenly in a greased 9-inch square baking pan. Bake in a preheated 350 degrees F oven for 25 to 30 minutes, or until top is dull and set. Let cool in pan on rack for 15 to 30 minutes, then cut into squares.