1. In the work bowl of a food processor fitted with the steel blade, pulse the confectioners’ sugar with the almonds repeatedly for 3 or 4 minutes. The nuts should be ground very fine and there shouldn’t be any discernible pieces of almond left. As you are grinding, stop the machine occasionally and scrape down around the inside and bottom of the work bowl with the end of a narrow metal spatula to dislodge any of the ground mixture caked there. Pour the ground mixture into a bowl.
2. Half-fill a saucepan with water and bring it to a boil over medium heat. Lower to a simmer. In the bowl of a standing electric mixer combine the egg whites, granulated sugar, and water. Place the bowl on the pan of water and whisk gently until the egg whites are hot and the sugar is dissolved. Place the bowl on the mixer fitted with the whip attachment and beat until cooled and stiff.
3. Gently fold in the almond and sugar mixture and the corn syrup into the meringue. Fold in several drops of food coloring. The macaroon paste should be tinted a deep pink.
4. Using a pastry bag fitted with a ½-inch plain tube (Ateco #806), pipe 1½-inch macaroons onto the prepared pans. Leave about an inch around each cookie in all directions. Let the macaroons dry, uncovered, at room temperature for an hour.
5. When you are ready to bake the macaroons, set racks in the upper and lower thirds of the oven and preheat to 300 degrees. The macaroons will be baked only in the lower third. Place one empty pan on the upper rack of the oven to protect the macaroons from the top heat, then place another empty pan on the lower rack so that the macaroons will bake on two pans and be protected from the bottom heat. Place a pan of macaroons on the lower pan and bake for 10 to 12 minutes, or until the macaroons are risen and are smooth and crackled around the edges that meet the pan. Remove the pan with the macaroons on it to a rack to cool. Place the second pan of macaroons in the oven on the pan that is still on the lower rack and bake the remaining macaroons.
6. While the macaroons are cooling, heat the jam to a simmer in a small saucepan on medium heat, stirring often.
7. After the macaroons have cooled, detach them from the paper and sandwich them together, using about ¼ teaspoon of the jam for each pair.
8. Store the sandwiched macaroons between sheets of parchment or wax paper in a tin or plastic container with a tight-fitting cover.