Preheat oven to 350°F (175°C). Line three 9x13 inch baking pans with parchment paper.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
Combine the flour, baking powder, and salt; stir into the creamed mixture. Divide the dough into three equal parts. Mix one part with red food coloring, one with green, and leave the third plain.
Spread each portion of dough evenly into the prepared pans.
Bake for 10 minutes in the preheated oven, or until lightly browned. Remove from the oven and let cool completely.
Place the green layer on a sheet of waxed paper. Spread with half of the jam. Place the plain layer on top, and spread with remaining jam. Top with the red layer.
In a microwave-safe bowl, melt the chocolate, stirring occasionally until smooth. Spread over the top of the red layer. Let the chocolate set, then cut into small squares.