Whisk in egg yolks and bourbon. Combine egg whites with cream of tartar in a medium-size bowl. Beat at medium speed until soft peaks form. Gradually sprinkle in remaining sugar and beat at high speed until the mixture is stiff but not dry. Whisk flour and pecans into chocolate mixture.
Scrape batter into prepared pan.
Bake 30 to 35 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs clinging to it. Cool in the pan on a wire rack. Cake may be stored at room temperature for one day before serving. Leave cake on the bottom of the pan and transfer it to a serving dish. Sieve powdered sugar very lightly over the top.