Line an 8×8 pan with parchment and spray with nonstick spray.
Divide the condensed milk between two bowls with white and semi-sweet chocolate chips.
Microwave the semi-sweet chocolate mixture in 30-second bursts, stirring each time.
Stir in 1 tsp vanilla, then spread this layer in the pan.
Microwave the white chocolate mixture in 30-second bursts, stirring each time.
Add 1 tsp vanilla, mix in sprinkles, and spread over the semi-sweet layer.
Top with more sprinkles, then chill for 1 hour before slicing.