Preheat an oven to 170 degrees C. Line a 20cm square baking pan with baking paper.
Combine the raisins and rum in a small bowl; set aside to soak.
Heat the whipping cream in a small pot over medium-low heat until hot, but do not allow to boil. Remove from heat and stir the chocolate chips into the hot cream until completely melted. Set aside to cool.
Sift the flour, brown sugar, cocoa powder, baking powder and cinnamon together into a bowl. Beat the eggs into the flour mixture individually; mix gently. Stir the chocolate mixture into the flour mixture until incorporated. Fold the raisins, any remaining rum, and the pecans into the batter; spread into the prepared baking pan.
Bake in the preheated oven until the top is dry and the edges have started to pull away from the sides of the pan, about 30 minutes.