In a mixing bowl, whisk together the almond flour, all-purpose flour, sugar, and salt. Pour in the melted butter and stir with a fork until the butter is fully distributed and the mixture holds together when pinched.
Firmly press the crust mixture against the bottom and sides of a 9-in (23 cm) tart pan with a removable bottom. Bake the crust for 20 minutes, or until golden brown. Transfer to a wire rack and let cool completely.
For the clementine and dark chocolate ganache: Melt the Chocolats Favoris Original Dark Fondue according to the packaging instructions. While the fondue is melting, in a saucepan, whisk together the heavy cream, butter, marmalade, and juice. Warm until hot, then remove from the heat (do not boil.)
Once the fondue is melted, open the can and pour the melted dark chocolate into the hot cream. Whisk until smooth.
To assemble: Spread the clementine marmalade all over the bottom of the cooled crust. Pour the clementine and dark chocolate ganache into the crust and smooth out the top. Refrigerate the tart for at least 3 hours, or until the ganache is fully set. Bring the tart back to room temperature at least 30 minutes before serving. Garnish with clementine slices or zest, to taste.