Ingredients

Scale

1 3/4 cups (230g) all purpose flour
1/4 cup (30g) cornstarch
1 cup (100g) unsweetened cocoa powder
2 tsp baking soda
1 tsp baking powder
1/2 tsp kosher salt
1 cup (200g) granulated sugar
1 cup (205g) dark brown sugar, packed
1/2 cup (108g) vegetable oil
1 cup (230g) mayonnaise
3 large eggs + 1 egg yolk
1/2 cup (128g) milk
1 tbsp vinegar
2 tsp vanilla extract
1 cup (240g) hot coffee (or 1 cup hot water + 2 tsp instant espresso powder)
2 cups (450g) unsalted butter, room temp
1 1/2 cups (165g) powdered sugar
3 tbsp corn syrup
1 tsp vanilla extract
Pinch of kosher salt
3/4 cup (177g) warm water
3/4 cup (75g) dutch process cocoa powder (or unsweetened cocoa powder)
10 oz dark chocolate chips (one bag), melted and cooled slightly

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Instructions

Preheat the oven to 350°F and prepare three 8" cake pans by greasing and lining with parchment paper.
In a medium bowl, whisk the all-purpose flour, cornstarch, cocoa powder, baking soda, baking powder, and salt together. Set aside.
Mix the milk, vinegar, and vanilla in a measuring glass and set aside.
In a large mixing bowl, combine the granulated sugar, dark brown sugar, vegetable oil, and mayonnaise. Add the eggs and egg yolk, whisking until smooth.
Incorporate the milk mixture into the sugar mixture.
Add half of the dry ingredient mixture and whisk until combined.
Pour in the hot coffee and whisk, followed by the addition of the remaining dry ingredients. Ensure the batter is thin and liquidy.
Divide the batter evenly among the three prepared pans.
Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean with a few moist crumbs.
Let the cakes cool in the pans for about 10 minutes. Run a knife around the edges, turn them out onto a cooling rack, and cool completely before frosting.

Notes

Make sure the eggs are at room temperature for better incorporation.
You can substitute hot coffee with hot water mixed with instant espresso for a deeper flavor.
This cake can be made a day in advance and stored wrapped in plastic.
Adjust baking time if using a different cake pan size.

Nutrition

Serving Size: 1 slice
Calories: 480
Sugar: 42g
Sodium: 250mg
Fat: 24g
Saturated Fat: 7g
Unsaturated Fat: 17g
Trans Fat: 0g
Carbohydrates: 67g
Fiber: 3g
Protein: 6g
Cholesterol: 55mg

Nutritional information is an estimate. The nutritional values for your final dish may vary based on measuring differences and products used.