8 ounces semisweet chocolate, divided
1/2 cup (1 stick) unsalted butter
1 orange
1 cup sugar
2 eggs
1 1/2 Tablespoon orange liqueur (I used Cointreau)
1 teaspoon vanilla extract
2/3 cup all-purpose flour
1/2 teaspoon baking powder
pinch of salt
2/3 cup cup coarsely chopped roasted hazelnuts
5 slices candied orange peel, cut into pieces (recipe to follow)