Black Pepper and Chocolate Mousse Cake

Name: Black Pepper and Chocolate Mousse Cake
Ingredients: ¾ cup ground almonds; 4 tbsp natural unsweetened cocoa powder (not dutch processed); 4 tbsp all-purpose flour; 1 pinch salt; 2 eggs; ½ cup granulated sugar; ⅓ cup vegetable oil (eg, canola, peanut, sunflower etc but not olive); ⅓ cup sour cream; 4 eggs, separated; 2 tbsp freshly cracked black pepper + more to sprinkle on top; ⅔ cup (150ml) double cream; 10 oz (about 300gm) dark bittersweet chocolate; 2 tbsp powdered sugar (granulated sugar ground in a processor)