Heat-treat the dry cake mix: microwave in a large bowl in 30-second bursts, stirring, until it reaches 165°F. Cool completely.
Beat cream cheese in a mixing bowl until smooth and fluffy.
Whisk in yogurt, milk, vanilla, and salt until creamy.
Blend in the cooled cake mix until fully incorporated and no dry spots remain.
Fold in the whipped topping gently to keep it airy.
Stir in sprinkles just until dotted throughout. Chill 20–30 minutes, then top with extra sprinkles and serve.