For the caramel-banana: Cut the banana into slices a little less than 1 cm.
Melt butter together with sugar in a saucepan. Add sliced banana and cook over low heat until browned on one side, shaking the pan occasionally.
When the banana is nicely browned, turn over and brown the other side. Remove to a plate and cool.
Take the frozen puff pastry out of the freezer and let stand at room temperature for 5~10 minutes. Cut each sheet into 4 even pieces.
Prick the pastry with a fork. ※If the pastry already has holes in it, skip this step.
Break the chocolate into 8 pieces. Place a square of chocolate on the pastry, leaving about 1cm bare on the sides.
Put a slice of caramel-banana on top of the chocolate.
Fold over the pastry and press the edges firmly together with a fork. If you brush the edges with egg yolk first, they'll stick together.
Put the pies on a parchment-lined baking sheet and brush with egg yolk. Bake at 410°F/210°C for 10 minutes.
Lower the heat to 360°F/180°C and bake for 15 minutes. Done!
Of course, you can use plain banana, or just chocolate. It's also fun to make 3 different kinds, so the inside is a surprise.
Story Behind this Recipe
It's almost Valentines Day. I tried making a chocolate pie version, using ever-easy frozen puff pastry. It's good with plain bananas on top too, but I added the extra step of caramelizing the banana.
※Use dark chocolate. ※Please note that there are times when the pies stay closed beautifully, or times when some of the filling escapes, like in the top photo, even though you closed them firmly, in Step 9. ※Adjust the amount of sugar according to the ripeness of the bananas.