Line an 8 x 8 dish with foil or parchment paper. Set aside.
Combine the sweetened condensed milk, chocolate chips, and cake mix in a medium saucepan over medium heat.
Stir frequently until the chocolate has melted and the mixture is smooth.
Remove from heat and stir in half of the sprinkles.
Pour into the prepared pan and immediately sprinkle with remaining sprinkles.
Refrigerate for 2 hours.
Cut into 25 squares and enjoy.