Could I have the recipe for Classic Yellow Cake?
Here's a recipe for Classic Yellow Cake:

Ingredients:

Cake

• 1 stick unsalted butter, room temperature
• 1 1/2 cups granulated sugar
• 3 large eggs
• 1 large egg yolk
• 1 teaspoon vanilla extract
• 2 1/4 cups all purpose flour
• 2 teaspoons baking powder
• 1 teaspoon baking soda
• 1 teaspoon kosher salt
• 1 1/4 cups buttermilk

Frosting

• 1 1/2 sticks unsalted butter, room temperature
• 1/2 cup unsweetened cocoa powder
• 1/2 teaspoon kosher salt
• 3 1/2 cups powdered sugar
• 1/3 cup whole milk, plus 1 tablespoon
• 1 teaspoon vanilla extract
• rainbow sprinkle, for decorating

Instructions:

1. Preheat the oven to 350°F (180°C). Grease and line 2 9-inch (22 cm) round cake pans with parchment paper.
2. In a large bowl, cream the butter and sugar with an electric hand mixer on medium speed until light and fluffy, 3–5 minutes, stopping to scrape down the sides of the bowl 2–3 times. Add eggs and the egg yolk, 1 at a time, beating for 30 seconds between each addition, or until just combined. Add the vanilla and beat until incorporated.
3. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
4. Add 1/4 of the dry ingredients to the batter and beat on medium speed for about 30 seconds, or until fully combined. Add 1/4 of the buttermilk and mix for another 30 seconds, until well incorporated. Continue alternating with the remaining dry ingredients and buttermilk. Beat for 3 minutes more.
5. Divide the batter evenly between the prepared pans. Bake the cake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Remove the cakes from the oven and let cool slightly, then remove from the pans and let cool completely on a wire rack.
6. Make the frosting: In a large bowl, cream together the butter, cocoa powder, and salt with an electric hand mixer on medium speed until very thick and well incorporated, about 3 minutes. Scrape down the sides of the bowl.
7. Turn the mixer speed to low and gradually alternate adding the powdered sugar and milk. As the sugar is incorporated, increase the speed of the mixer. Add the vanilla and beat until the frosting is smooth and fluffy, about 1 minute.The frosting will keep in an airtight container in the refrigerator for up to 1 week. Bring to room temperature before frosting the cake.
8. Add a small dollop of frosting to a cake stand. Arrange four pieces of parchment paper around it. Place 1 cake round on the stand. Add a large dollop of frosting to the top of the first cake and spread evenly. Add the remaining cake layer on top and frost completely.
9. Decorate the top with rainbow sprinkles, if desired.
10. Remove the parchment paper. Slice and serve.

Enjoy your Classic Yellow Cake!