Preheat your oven to 350°F (175°C).
Grease your Bundt pan with cooking spray or butter and a light dusting of flour.
In a large mixing bowl, combine the yellow cake mix and the instant vanilla pudding mix. Stir until well mixed.
Add the sour cream, eggs, water, and vegetable oil to the dry ingredients. Beat on medium speed until smooth and creamy.
Gently fold in the rainbow sprinkles into the batter.
Carefully pour the batter into the prepared Bundt pan and spread it evenly.
Bake for 45-55 minutes, or until a toothpick inserted comes out clean.
Allow the cake to cool in the pan for 10-15 minutes before inverting onto a wire rack to cool completely.
Prepare the frosting by beating the softened cream cheese and unsalted butter until creamy. Gradually add powdered sugar, salt, and vanilla extract, mixing until smooth.
Once the cake is cooled, drizzle the cream cheese frosting over the top and sprinkle additional rainbow sprinkles for garnish.
