Preheat oven to 375° F. Remove on of the pie crust rolls from the box unroll onto a lightly floured surface. Lightly flour a rolling pin and roll the pie dough out to be thinner. Perhaps an additional inch or two in diameter.
Use a round cookie cutter slightly larger than the individual molds in the tart pan and press down firmly as many times as necessary to fill your tart pan. Use the small cookie cutters to cut out small shapes to place on top of jam.
Use a thin stainless steel spatula to lift the round dough pieces into the tart molds. Press gently into each mold, shaping it to your desired shape.
Add about 1 Tbsp of jam to each shaped tart and spread evenly. The amount of jam to dough will vary based on your molds. The goal is enough jam that the tart doesn’t taste too doughy, but not so much that it bubbles over. 3/4 of the way to the top of the mold is a good estimate. If using small shapes, press them lightly into the jam at this time.
Whisk the egg and use a basting brush to spread the egg wash around the rim of the dough and onto the center shapes. This is to add the golden color, not for taste. You can also just use the egg white, or the egg yolk with a bit of water. Each egg wash gives a slightly different browning color.
Bake for 15 minutes, checking to see if jam is bubbling over. Remove when dough is golden brown. It may take 15-20 minutes, depending on your oven and how thin you rolled out the dough. Cool thoroughly, the jam gets very hot!