So simple, so quick, and so ridiculously delicious.
Preheat oven to 400 degrees.
Place your rectangle vertically in front of you.
Spoon one to two tablespoons of jam on to the lower half of the rectangle and spread it out slightly giving yourself a half of an inch buffer away from the sides so the pastry can seal properly.
Fold over the upper portion of the puff pastry onto the lower half and lightly press around the outside to seal it. Using a fork, press the tines around the outsides of the dough, crimping the crust and sealing the jam in tight.
Next, using a knife poke 3 holes in the top of the crust to allow for hot air to escape. This will also prevent the jam from breaking out the edges.
Repeat with remaining rectangles.
Bake on a sheet tray in the oven for about 25 minutes or until puffy and deeply golden brown.