This is just to say that if you have an inkling that you should throw a ton of mini chocolate chips into your yellow cake batter…well, you should follow that urge.
And if, once baked, you’d like to paint the cake layers with simple syrup and sandwich them with a trusty chocolate buttercream and some more mini chocolate chips (for texture & fun, duh), you should absolutely do that, too.
And if you feel like you want to frost the whole thing per usual layer cake practice, go right ahead. But if you want to leave it a little naked and rustic, you should—you guessed it—follow that instinct.
And if, at the end of this process, you’ve found that you’ve made a triple-decker Chocolate Chip Cake for no real reason, well, you’re not alone. I did, too.
Chocolate Chip Cake
makes one 3 layer 9-inch round cake
2 1/2 cups all-purpose flour
1/4 cup cornstarch
1 1/2 cups granulated sugar
1/3 cup light brown sugar, packed
2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon Kosher or sea salt
1 cup mini chocolate chips
1 cup (2 sticks) unsalted butter, softened to room temperature, cut into pieces
3 large eggs + 2 large egg yolks, room temperature
1 tablespoon pure vanilla extract
1 cup whole milk
1/3 cup full-fat sour cream
1/4 cup water
1/4 cup granulated sugar
3 ounces dark chocolate
1 cup (2 sticks) unsalted butter, softened to room temperature
1 1/2 cups confectioner’s sugar
1/2 cup natural unsweetened cocoa powder
1/4-1/2 teaspoon Kosher or sea salt
1 1/2 teaspoons pure vanilla extract
2 tablespoons heavy cream
For Assembly & Garnish:
1/2-2/3 cup mini chocolate chips (or more, if desired), divided
Place an oven rack in the center position. Preheat oven to 350F.
Grease three 9-inch round cake pans. Line with parchment and grease again. Set aside.
Make the cake batter. Combine flour, cornstarch, granulated sugar, light brown sugar, baking powder, baking soda, and salt in a large mixing bowl. Whisk ingredients together (I like to do this by running my mixer on its lowest speed for about a minute). Add mini chocolate chips and mix to distribute.
Add butter to dry ingredients. Gradually turn the mixer from low up to medium, to mix in the butter until there are no large pieces and the texture is rubbly. This will take a few minutes.
With the mixer running, add eggs and yolks one at a time, followed by vanilla. Mix until combined.
In a measuring cup or small mixing bowl, use a fork to whisk together milk and sour cream. Running the mixer on medium, add the milk mixture in two installments and mix until combined. Scrape down the bowl well to ensure even mixing.
Divide batter evenly among prepared pans. Tap each full pan on the counter five times to release any large air bubbles. Bake layers on the center rack for 25-27 minutes, or until a toothpick inserted in the centers comes out clean. Let let layers cool in their pans for 15 minutes. Run a thin knife around the edges of the layer before turning out onto a rack to cool completely.
Make the simple syrup. Combine water and sugar in a small saucepan. Heat over medium heat, stirring occasionally, until sugar has dissolved (about 4-5 minutes). Remove from heat. Set aside.
Make the Chocolate Frosting. For a thicker coat or for piping, make 1.5x the recipe as written. Place chopped dark chocolate in a small microwave-safe bowl. Microwave in 15 second increments, stirring just until melted. Cool to room temperature (this can be done quickly by putting it into the fridge for 5-8 minutes, then whisking quickly with a fork).
In a large mixing bowl, use an electric mixer to beat butter until very light and fluffy (about 4-5 minutes). Beat in confectioner's sugar, followed by cocoa powder and salt, scraping down the bowl as necessary. Mix in melted chocolate, followed by vanilla and heavy cream. Beat on high for 1-2 minutes, until very fluffy.
Assemble the cake. Place the base layer on a serving plate. Paint the top with 1/3 of the simple syrup. Let soak in for a minute or two. Top the layer with a thin layer of frosting (about 1/3 of the batch), then top with 2 tablespoons of mini chocolate chips. Repeat this process with the remaining two layers. Frost the outside as desired, then decorate with more mini chocolate chips.
Layer cake will keep covered at room temperature for up to three days, or in the refrigerator for up to five.