To make the crust: Follow the instructions for the chocolate dough recipe below. Roll the dough out between two pieces of parchment paper into a thin round about 12 inches across and no thicker than ⅛ inch. Gently release the dough from time to time as you work. Fit the dough into a 9-inch tart pan with a removable bottom. Chill the crust for 15 minutes in the freezer or at least 30 minutes in the refrigerator.

To blind-bake the crust: Preheat the oven to 325°F. Line the crust with tin foil and then fill it with pie weights. Bake the crust until it looks set, about 20 minutes. Remove the foil and weights and bake until the crust is fully cooked, about 20 minutes more. Allow the crust to cool completely in the pan on a wire rack.

To make the filling: First make a caramel by putting the corn syrup in a heavy-bottomed saucepan and cooking it over medium heat until bubbles appear around the edges. Stir in a third of the sugar. When it begins to look like wet sand, add another third of the sugar; continue cooking until that begins to dissolve, then add the remaining sugar. Cook the caramel without stirring until it turns deep amber, 15 to 20 minutes. Remove the pan from the heat and carefully whisk in the butter, a piece at a time. Whisk in the crème fraîche, salt, and vanilla. Stir in the peanuts and immediately pour the caramel into the tart shell. Set it aside to cool to room temperature.

To make the ganache: Bring the cream to a simmer in a saucepan over medium-high heat. Put the chopped chocolate in a liquid measuring cup. Fold the cream into the chocolate and stir just until the ganache is smooth and shiny. Pour the ganache evenly over the cooled caramel. Allow the tart to set for at least an hour before slicing and serving.