Preheat the oven to 300 F.
Grease a square mold of 8″ (20 cm) and set aside.

Mix the flour, salt, and cinnamon. Set aside.

Put the raisins in a small saucepan with the water, bring to a boil, and cook until the water has almost completely evaporated.
Add the rum, cook for another 30 seconds. Remove from heat and flambé the raisins.

Melt the chocolate in a bain-marie, stirring occasionally.
Remove the bowl from the bain-marie and add the butter, stirring until it is melted. Set aside.

Beat the eggs and sugar with an electric mixer until the mixture is pale, about 2 minutes.
Reduce the mixer speed and add the chocolate-butter mixture, mixing only until everything is incorporated.
Add the dry ingredients and mix at low speed for about 30 seconds.
Add the raisins and mix with a spatula.

Spread the preparation in the reserved mold and bake for 50 to 60 minutes or until the top is dry and cracked and a knife inserted in the center comes out clean.
Let cool on a rack at room temperature.

Unmold and cut into 16 squares.

Serve warm or cold with ice cream or whipped cream or custard.