Preparation:

1. Preheat the oven to 375 degrees F.  Line a cupcake pan with paper liners. 
2. In a medium bowl, stir together the flour and salt.
3. In an electric mixer with the whisk attachment, beat the egg whites and cream of tartar to form soft peaks.  With the mixer at medium speed,  gradually add the sugar.  Beat at high speed to stiff, glossy peaks.  Lower the speed and mix in the vanilla.  Fold in the flour mixture in 3 additions, taking care to deflate the batter as little as possible.  Quickly fold in the chopped Baci.  Divide the batter among the cupcake pan and smooth out the tops.
4. Bake until the tops are golden and a toothpick inserted into the middle of the cupcake comes out clean, about 15 minutes.  Cool on a wire rack for 5 minutes; then remove the cupcakes from the tin to cool completely.
5. While the cupcakes cool completely, make the glaze.  Put the chopped chocolate into a small bowl.  Bring the cream to a simmer and pour over the chocolate; shaking the bowl to submerge the chocolate.  Let sit 5 minutes; then whisk until smooth.  Stir in the hazelnut liqueur, if using.
6. Spoon the glaze on the cupcakes and smooth to the edges.  Sprinkle with the chopped Baci.  Refrigerate until the glaze is set.
*Cooks Note: The Baci will be easier to chop if they are cold, so place them in the refrigerator for a few hours before you make the cupcakes.
NOTE: this makes more glaze than you will probably need.  Refrigerate any unused glaze; reheat in the microwave.