One ½ sheet pan with prebaked graham crust shell - cooled – recipe below
Preheat oven to 350ºF (180ºC.)
Spread the sugar in an even layer in the bottom of a large, heavy-duty saucepan or Dutch oven. Cook the sugar over moderate heat until the edges liquefy and being to caramelize. Use a heatproof utensil to gently drag the liquefied sugar toward the center of the pan, encouraging the sugar to melt evenly.
Once the sugar is melted, it was caramelize rather quickly. When it starts to smoke, but before it burns, turn off the heat and stir in the coffee. (The mixture will bubble and seize a bit. Be sure to avert your face and you may wish to wear oven mitts.)
If the caramel has seized up in places, stir it gently over low heat until smooth. Then add the butter and salt, and stir until melted, then stir in both chocolates until smooth*.
Mix in the eggs, one at a time, then the flour. Stir in the rum.
Pour the mixture into the pre-baked tart shell, then bake for 15 to 20 minutes, just until the filling starts to rise and crack at the edges but the center is still jiggly. Do not overbake.
Remove from oven and let cool completely before slicing.
This needs to be made 1 day in advance.
Graham Crust Recipe
4 cups graham crumbs
1 cup melted butter
1 tblsp cinnamon
2 tblsp granulated sugar
2 tblsp brown sugar
Zest of 1 lemon, minced
Zest of 1 orange, minced
Pinch of fine salt
Combine melted all ingredients in a large mixing bowl and stir well to combine
Spread out onto a sprayed ½ sheet pan, lined with parchment paper and sprayed again.
Press crust mix down to make a solid, even crust layer.
Bake @ 350 for 5-6 minutes and let cool before topping with chocolate mixture and finishing tart.