Ingredients:

  • 1 box (15.25 oz / 432 g) vanilla cake mix
  • 1 cup (240 ml) whole milk, at room temperature
  • 1/2 cup (113 g) unsalted butter, melted
  • 3 large eggs, at room temperature
  • 1 teaspoon pure vanilla extract
  • 1/2 cup (120 g) sour cream
  • 1/2 cup (113 g) unsalted butter, softened (for frosting, optional)
  • 3 cups (360 g) powdered sugar, sifted (for frosting, optional)
  • 1/4 cup (60 ml) heavy cream (for frosting, optional)
  • 1 teaspoon pure vanilla extract (for frosting, optional)

Instructions:

  1. Preheat the oven to 350°F (175°C).
  2. Grease the baking pan with butter or line with parchment paper.
  3. In a large bowl, combine the melted butter, milk, eggs, sour cream, and vanilla. Whisk until smooth.
  4. Gradually add the cake mix to the wet ingredients while whisking until just combined. Do not over-mix.
  5. Pour the batter into the prepared pan, smoothing the top with a spatula.
  6. Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
  7. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
  8. While the cake cools, beat the softened butter until creamy, then add powdered sugar, cream, and vanilla. Beat until smooth and fluffy.
  9. Once the cake is fully cooled, spread the frosting evenly on top and, if desired, decorate with sprinkles or fruit.