Center the oven rack in the middle and preheat the oven to 350 F (180 C).
Butter and flour the removable sides of a 9″ (23cm) round mold, and cover the bottom with parchment paper.

Combine the flour, baking soda, and salt, and set aside.
Melt the chocolate and butter in a double boiler and set aside.

Using an electric mixer, beat the eggs with the sugars.
Add the corn syrup, then the vanilla extract, and mix.
While mixing gently, add the chocolate mixture, then the reserved dry ingredients, and mix well.

Pour the preparation into the mold and bake for 40-45 minutes.
Remove the cake from the oven and let it cool completely on a rack.
When the cake is completely cool, invert it onto a serving plate.
Remove the parchment paper and put the removable sides of the mold back around the cake.
Pour the caramel and peanut sauce over the cake and let it cool to room temperature.

Caramel and peanut sauce:
In a saucepan, combine the sugar, water, and corn syrup, and bring to a boil.
Let cook until the color becomes amber, then remove from heat, add the cream and butter, and mix well.
Return to heat to melt any caramel pieces that have solidified.
Add the peanuts and mix.
Pour the preparation over the cake.