Preheat oven to 375 degrees F. and line a cookie sheet with parchment paper
Melt the 4 oz unsweetened chocolate in microwave or in a small bowl set over barely simmering water; set aside.
Combine both flours, sugar, cocoa powder, baking powder, and salt in bowl of food processor Pulse to mix. Add butter and pulse until mixture is a coarse meal. Dump into a mixing bowl. Alternatively, just mix the dry ingredients and shred the butter in with a grater.
Whisk 1/3 cup of the cream, molasses, egg, and vanilla together in another bowl. Pour over the flour mixture. Pour the melted chocolate over the egg mixture, then mix until everything starts to come together – there will be flecks of unmixed flour mixture here and there, but don’t overwork the dough by trying to mix them in. At this point, mix in the bittersweet chocolate
Turn dough onto a lightly floured or parchment lined surface and divide in half. Shape each half into a 5 inch 1 ½ inch thick square. Cut each square into four triangles. Carefully move the triangles to the baking sheet, setting them at least an inch apart. Brush with reserved whipping cream and sprinkle with sugar. Bake for 14-16 minutes. Cool at least 3 minutes on the baking sheet and then cool 3-4 minutes on a rack.