Make a ganache: In a small saucepan, bring the cream just to a boil.
Place 1/3 of the chocolate chips in a mug or small glass bowl. Add the cream to the chocolate chips; let set for 2 minutes; add 1 tsp butter and whisk until satiny. Let cool to room temperature, about 15-20 minutes.
In a large bowl, stir together the flours, baking powder, sugar, salt, and espresso powder.
Cut in the cold butter into the flour until small peas form. Stir in remaining 1/3 cup chocolate chips and optional nuts.
In yet another bowl, whisk together 3 Tbsp ganache to 2/3 cup light cream. Whisk together. It will appear a bit grainy. Pour into the flour mixture and mix together until there are no crumbs left on the bottom of the bowl. May need to add more light cream/milk.
On a clean work surface, pat out the dough into a 7x10 rectangle. Spread the remaining ganache over the outer two thirds of the dough.
Leave the middle third empty. Fold the rectangle like you would a letter. Once it's folded into thirds, pat down to a 1" thick rectangle.
Cut into wedges and place 2" apart on a parchment lined baking sheet. Optional: Brush tops with cream and sprinkle with coarse sugar.
Bake in preheated 400F oven for 8-10 minutes until golden brown. Allow to cool 5 minutes on baking sheets, then slide onto wire racks and allow to cool a further 10-20 minutes before serving.
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