Well, my Maltese Pastizzi experiment has been broadly a success. The filling was a huge pain but only because it was nine freaking hours of simmering the peas. I'm told this is because of the high calcium content of our water, and because the peas were old. Get better peas and put a new filter in the jug. On the whole, the only drawback is that the filling takes a long time to prepare, but it doesn't require too much attention. It's mostly just "put it in the fridge over night" sort of thing.
Soak about two cups of dry split peas in a bowl overnight. Then wash them in a colander to get the extra starch off. Then simmer in water with a cube and a half of mushroom stock, a blob of tomato paste and some fresh mint. Simmer until they're soft. If they stubbornly stay slightly crunchy, which happens frequently with dry split peas, just get them to the point where they're chewable and put about half of it in the blender, then back with the rest of the peas. Boil off the remaining extra water while you're standing over them stirring (that last bit is important; peas love to stick to the bottom of the pan and burn, then they're ruined because they also love to pick up the burnt flavour) until it's a nice thick paste. Let it cool to room temp or in the fridge over night.
I used a roll of store-bought puff dough. Take the roll out of the packet and off the wax paper. Roll it back up into a snake and cut the pieces about three or four inches long. With your hands coated in flour, just form them into the little envelopes and pinch them closed.
The pastry opened at the top as they baked, but you can fix that. Just a little egg wash will glue them closed, and if that doesn't work, you can just use a wee bit more dough and form a more bowl-like shape as in the video below. Dough pockets open on the top because as they bake the water boils off and the dough shrinks, so it pulls apart at the join, which is the weak spot. The solution is to stretch the dough pocket a little more when you're forming them.
On the whole, however, they really are just more or less the same as the ones we had in Malta, and they're really simple to make. Have with your tea in the morning like the Maltese do, or they'll go perfectly for 3 o'clock tea time or elevensies.
Just don't do it every day, or you'll be four hundred pounds by the end of the week.
Also, there's a song. A pastizzi song. Sing the song. It will cheer you up.
Not to Maltese standards of cheeryness, but I think that's impossible unless you have the right genes.