- Preheat oven to 300°F.
- Butter and line 8 x 8-inch square baking pan with parchment paper.
- Sift together flour, sugar, cocoa, and baking soda into large mixing bowl.
- In medium bowl, whisk together egg, sour cream, oil, soy sauce, and vanilla until well blended.
- Pour egg mixture all at once into flour mixture and stir with a stiff rubber spatula until just combined.
- Add boiling water and gently stir until blended and smooth. Pour into prepared pan.
- Bake 30 minutes, or until toothpick inserted near center is almost clean.
- Cool completely on wire rack. Remove cake from pan and place on serving plate.
For Chocolate Glaze:
- Combine cream and soy sauce in a small saucepan. Heat over medium heat, stirring constantly, until mixture just comes to a simmer (do not boil).
- Pour cream mixture over chocolate chips in a heat-proof bowl; let stand for 3 minutes.
- Gently stir with wire whisk until chocolate chips dissolve and mixture is blended. Let cool 5 minutes.
- Stir glaze and pour evenly over cooled cake. Let glaze set at least 30 minutes before serving.
