Preheat the oven to 350F. Position racks in the upper and lower thirds of the oven.

Combine the flour, baking powder, and salt in a small bowl, whisk to combine.

Place the 8 oz. of chocolate and the butter in a large heatproof bowl set over a pot of simmering water. Stir frequently until just melted and smooth. Remove the chocolate from the pan and set it aside. Leave the heat on under the pan with water.

In another large heatproof bowl, whisk the eggs, sugar, and vanilla together thoroughly. Set the bowl over the pan of hot water and stir until the mixture is lukewarm to the touch. Stir the egg mixture into the (now warm) chocolate. Stir in the flour mixture, then the chocolate chunks and nuts (I used almonds).

Scoop tablespoonfuls of batter and place about 1 ½ inches apart on parchment paper-lined cookie sheets.

Bake 12-14 minutes, until the surface of the cookie looks dry and set, and the centers are still gooey.

Set the pans on racks to cool. Can be enjoyed as soon as you can eat them without burning your mouth. :) Let the cookies cool completely before storing or stacking.