1. Sift together the corn flour and the oat flour.
2. In an electric mixer fitted with the paddle attachment, or in a bowl with a rubber spatula, cream the butter and salt on medium speed for about 1 minute. Scrape down the sides of the bowl with a rubber spatula and add the sugar, working to combine.
3. Scrape down the bowl and add the almond flour and vanilla extract. Gradually add the egg and one fourth of the flour mixture. Beat at low speed until just incorporated. Scrape down the bowl and gradually add the remaining flour and mix just until the dough comes together.
4. Divide the dough into 2 equal pieces. Place each piece between sheets of plastic wrap and gently roll out to a 10-1/2 inch circle. Place on a sheet pan and refrigerate for 1 hour or longer.
5. Preheat the oven to 325°F. Lightly butter a 9-inch tart pan or pie dish. Remove one sheet of dough from the refrigerator, and if it is very stiff set it out for about 5 minutes, until it is pliable. Ease the dough into the tart pan or pie dish. If the dough cracks, pinch the cracked edges together. The remaining dough can be refrigerated or frozen for another use.
6. With a fork, pierce the bottom of the crust in rows. Place the tart pan on a baking sheet and place in the oven on the middle rack. Bake 25 to 30 minutes, until lightly browned and dry. Allow to cool completely on a rack before filling.
7. Meanwhile, combine the cream, butter, sugar and salt in a small saucepan and heat until bubbles start to form around the edges.
8. Place the chocolate in the bowl of a food processor and pulse to chop. With the processor running, carefully pour the hot cream mixture into the chocolate. Scrape down the bowl and process again while adding the extract, coffee, and liqueur. Pour the mixture into the cooled crust and chill until firm.
9. Beat the cream, liqueur and sugar together in the chilled bowl of an electric mixer until smooth and stiffened. Spread the mixture over the chilled chocolate. Refrigerate until serving.