Preheat oven to 350 degrees and grease 3 (13” by 9”) baking pans. Line bottom of each with wax paper, letting it extend at 2 opposite ends, and grease paper. Break marzipan paste into small pieces and grind with sugar in food processor until no lumps remain. Transfer to a large bowl and add butter. Beat with an electric mixer until light and fluffy, then add yolks and almond extract and beat well. Beat in flour and salt on low speed. Beat egg whites in another bowl with cleaned beaters until they just hold stiff peaks and stir one third into batter to lighten slightly (batter will be stiff). Fold in remaining whites thoroughly. Divide dough into thirds (about 1 1/2 cups each). Stir green food coloring into one third and red into another, leaving one third plain. Spread each dough separately into a pan. (layers will be thin.) Bake layers in batches in middle of oven until just set and beginning to turn golden along edges, 7 to 10 minutes total. Run a knife along edges to loosen from pan, then while still hot, invert a large rack over pan and invert layer onto rack, pulling gently on wax paper overhangs to release if necessary. Peel off wax paper and let cool completely. Line a large shallow baking pan with wax paper and slide green layer into it. Spread half of jam evenly over green layer and carefully top with plain layer. Spread remaining jam evenly over uncolored layer and carefully top with the pink layer. Trim edges if needed. Cover with plastic wrap and weight with a large cutting board or baking pan. Chill at least three hours. Melt chocolate in a double boiler or a metal bowl set over a pan of barely simmering water. Remove weight and plastic wrap and spread chocolate evenly over top, but not sides, of pink layer. Let stand at room temp. until set, about 1 hour, and cut into small squares. (12 rows by 12 rows)
