Vegan Coca-Cola Cake

Ingredients

• Nonstick vegetable oil spray (for pan)
• 2 cups (400 g) granulated sugar
• 1¾ cups (219 g) all-purpose flour
• 1 cup (84 g) Dutch-process cocoa powder (such as Guittard Cocoa Rouge)
• 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt
• 1¼ tsp. baking powder
• 1¼ tsp. baking soda
• 1 tsp. arrowroot
• ⅔ cup vegan sour cream
• ½ cup vegetable oil
• 2 tsp. vanilla extract
• 1¼ cups Coca-Cola
• 1 Tbsp. fresh lemon juice
• ½ tsp. ground cardamom (optional)
• 4 oz. bittersweet chocolate, chopped, or chocolate chips
• ⅓ cup plus 1 Tbsp. Coca-Cola
• ¾ cup (1½ sticks) vegan butter, room temperature
• 2 cups (220 g) powdered sugar
• ¾ tsp. Diamond Crystal or ½ tsp. Morton kosher salt

Steps

1. Place a rack in middle of oven; preheat to 350°. Lightly coat a 13×9" metal baking pan with nonstick vegetable oil spray and line with parchment paper, leaving overhang on long sides. Whisk together 2 cups (400 g) granulated sugar, 1¾ cups (219 g) all-purpose flour, 1 cup (84 g) Dutch-process cocoa powder, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, 1¼ tsp. baking powder, 1¼ tsp. baking soda, and 1 tsp. arrowroot in a large bowl. Add ⅔ cup vegan sour cream, ½ cup vegetable oil, and 2 tsp. vanilla extract and mix until barely combined. (Be careful not to overmix; mixture will resemble wet sand and be somewhat dry. Large pockets of unincorporated flour are okay at this point.)
2. Microwave 1¼ cups Coca-Cola, 1 Tbsp. fresh lemon juice, and ½ tsp. ground cardamom (if using) in a small microwave-safe bowl on high until mixture is bubbling, about 90 seconds. (Alternatively, heat in a small saucepan over medium-high until gently boiling.) Stirring gently, slowly pour into batter; stir gently until smooth. Scrape batter into prepared pan and bake until a tester inserted into the center comes out clean, 35–45 minutes. Transfer pan to a wire rack and let cake cool in pan.
3. Meanwhile, place 4 oz. bittersweet chocolate, chopped, or chocolate chips in a large heatproof bowl. Microwave ⅓ cup plus 1 Tbsp. Coca-Cola in a small microwave-safe bowl on high until hot but not boiling, about 1 minute; pour over chocolate and vigorously whisk until chocolate is melted and mixture is smooth and emulsified. (If chocolate is not completely melted, microwave on high in 10-second bursts, stirring after each, until completely melted.) Chill until somewhat firm (like a soft ganache), about 20 minutes.
4. Beat ¾ cup (1½ sticks) vegan butter, room temperature, in the bowl of a stand mixer fitted with a paddle attachment on medium speed until fluffy, about 3 minutes. Add chocolate mixture and continue to beat on medium until incorporated and smooth, about 3 minutes. Turn motor off, add 2 cups (220 g) powdered sugar and ¾ tsp. Diamond Crystal or ½ tsp. Morton kosher salt. Mix on medium speed until frosting is fluffy and smooth, about 3 minutes.
5. Scoop frosting on top of cake and smooth into an even layer.