As much Sterling caviar as you can get your hands on.
To make the crust:
Preheat oven to 300 degrees. Arrange rye bread slices on baking sheet fitted with a wire rack and bake for 20 minutes or until slices are completely dry and brittle. Put toasted rye slices and cocoa nibs in food processor and pulverize until mixture takes on the texture of coarse sand. In a mixing bowl, combine rye and nibs with melted butter, sugar and salt and stir to combine. Mixture should be slightly moist and clump together when squeezed in your hand (think traditional graham cracker crust). Add additional melted butter if mixture is too dry. Press mixture onto the bottom and sides of a 4″ x 12″ rectangular tart pan with removable bottom. Increase oven temperature to 350 and bake for 10 minutes, or until the crust begins to smell a little bit like brownies. Remove from oven, let cool, and push tart shell out by the bottom.
To make the filling:
In a stand mixer fitted with the paddle attachment, beat the cream cheese and creme fraiche together on high until mixture is well combined. Stir in zest, maple syrup, and salt.
Pour filling into tart and distribute evenly with a spatula.