1 cup butter
1 1/4 cups white sugar
3 eggs
2 teaspoons vanilla extract
1 cup plain yogurt
1 3/4 cups all-purpose flour
3/4 teaspoon baking soda
3/4 teaspoon baking powder
1/4 teaspoon salt
2 tablespoons grated orange zest
2 (1 ounce) squares unsweetened chocolate, melted
2 tablespoons orange liqueur
2 tablespoons orange juice