Position oven rack in the bottom third of the oven and preheat to 375. Spray the bottom and sides of the pan very lightly with vegetable oil spray.
In a clean dry food processor or blender, pulverize pecans and flour until the mixture resembles the texture of fine meal. Set aside.
In a large mixing bowl, combine chopped chocolate, cocoa, and 3/4 cup sugar. Add boiling water and whisk until chocolate is completely melted. Whisk in egg yolks and Bourbon. Set aside.
Combine egg whites with cream of tartar in a medium mixing bowl. Beat on medium speed until soft peaks form. Gradually sprinkle in remaining sugar and beat on high speed until stiff but not dry. Whisk the flour and almonds into the chocolate mixture. Fold about one quarter of the egg whites into the chocolate mixture to lighten it. Fold in the remaining egg whites. Scrape batter into prepared pan; level the top if necessary.
Bake 30 to 35 minutes or until toothpick or wooden skewer plunged into the center comes out with a few moist crumbs clinging to it. Cool in the pan, on a wire rack. Cake will sink like a souffle and the top crust may be broken and uneven. Cooled cake may be covered and stored at room temperature or in the refrigerator one day ahead or frozen up to two months.
To unmold and serve: Detach the cake from the pan by sliding a small knife around the sides of the cake, pressing close to the sides of the pan. Release the spring and remove the pan sidesif the cake edges crack or break, do not eat or discard the pieces! Leave the cake on the bottom of the springform and transfer it to a serving dish. Gently replace any broken crust pieces. Sieve powdered sugar very lightly over the top to highlight the uneven surface and give the cake a rustic and appetizing appeal!