Preheat oven to 350°F. Grease one 8-inch or 9-inch cake pan with nonstick baking spray and line the bottom with parchment paper.
In a large bowl, sift together 1 ¼ cup (156 grams) all-purpose flour, 1 cup (200 grams) granulated sugar, ½ cup (55 grams) unsweetened cocoa powder, 1 ¼ teaspoon baking soda, ½ teaspoon ground cinnamon, ½ teaspoon ground cardamom, and ½ teaspoon salt.
In another bowl, whisk together ⅔ cup (140 grams) sour cream and 2 large eggs, then whisk in the ½ cup (50 grams) olive oil and finally ⅔ cup (150 grams) coffee. Pour into the bowl with the dry ingredients and whisk until no streaks of dry ingredients remain. Do not overmix, it's ok if there's a few lumps.
Pour the batter into the prepared cake pan and bake until a toothpick inserted into the center comes out clean with a few moist crumbs, about 25-30 minutes. Let cool in the pan for 10 minutes, then remove and place on a wire rack to cool completely.
While the cake is cooling, make the ganache. Heat the 1 cup (227 grams) heavy cream until steaming (about 1 minute in the microwave). Place the 1 ¼ cup (212 grams) semi-sweet or bittersweet chocolate in a bowl and pour the hot cream over the top and make sure all of it's covered, then let it sit for 5 minutes.
Stir the ganache until smooth. It may take up to 1 minute, but keep stirring and the melted chocolate will eventually combine completely with the cream. If any solid bits of chocolate remain, microwave in 15 second bursts. Stir in 1 tablespoon (33 grams) light corn syrup and ½ teaspoon ground cardamom.
Let the ganache cool in the bowl 20-30 minutes, stirring occasionally (the more you stir, the faster it will cool). You can also stir it over an ice bath. Cool the ganache only until it starts to hold peaks and has texture like frosting.
Place the cooled cake on a cake stand or plate and top with ganache. Use a spatula to spread and swirl it into an even layer. Top with Chopped pistachios, if desired.
Cake can be sliced and enjoyed immediately, but will keep in an airtight container for up to 5 days (It's best within 1-2 days). No need to refrigerate.
- A note about coffee in this recipe: It doesn’t give this cake a coffee flavor at all, but instead enhances the chocolate flavor. If you're not a coffee drinker, having instant coffee or instant espresso in your pantry for recipes like this is a great option. You can also substitute with water, but I highly recommend using coffee.
Calories: 497kcal, Carbohydrates: 49g, Protein: 6g, Fat: 32g, Saturated Fat: 14g, Polyunsaturated Fat: 2g, Monounsaturated Fat: 14g, Trans Fat: 0.02g, Cholesterol: 70mg, Sodium: 282mg, Potassium: 271mg, Fiber: 4g, Sugar: 31g, Vitamin A: 504IU, Vitamin C: 0.3mg, Calcium: 60mg, Iron: 3mg