Crumble the cupcakes, or take a cake and cut it into pieces, then add a layer into the base of each push-pop container.
Combine softened butter, powdered sugar, vanilla, and milk, and mix until the mixture is smooth. Then, pipe a thin layer onto the cake.
Spoon 1 tbsp jam into the center of each container, being careful not to touch the edges.
Place another layer of cake on top to seal in the jam, then add more frosting on top.
Cool it for 1 hour so the jam sets. Instruct guests to press the button for the reveal.