Seriously. These look (and sound) so posh and nice, but they're really quick and easy to assemble. I made them for my Business Communications class, and they vanished. There are only a few ingredients, and buying the more work-intensive ones pre-made makes ABSOLUTELY NO difference in the flavor and saves tons of time.
Preheat the oven to 350°F
Clean mushrooms as necessary, and chop them into small pieces. Heat a nonstick skillet with a drizzle of oil until just below the smoking point. Add the mushrooms and watch 'em sizzle. They will start to release a lot of water -- let them. The high heat will cook it off fairly quickly, and then they will darken and shrink. You may need to add a little more oil, as mushrooms are like tiny sponges around fats once they've shrunk down. When they are done, turn off the heat and transfer to a mixing bowl.
Some jarred roasted peppers are whole/halved or in long strips. Chop them up until they're close in size to the mushrooms, then toss it in.
Add the grated cheese to the bowl and mix thoroughly. The cheese may melt slightly due to the heat from the 'shrooms. This is perfectly fine and will probably smell delicious. Fend off hungry family members with a spatula.
Add the chopped parsley, which will add a lovely bit of green to the mix. Season to taste with salt and pepper.
Remove one roll of pastry from its cardboardy prison. If it is anything like mine, it is folded into thirds, with two folded sheets per box. You can cut along each fold, and then cut the remaining rectangle into thirds again to get a total of nine squares (they will not be perfect squares. This is okay). If they dry out a little too much, dab some water on them and wait a few minutes.
Take one square of pastry and dab a bit of water around the edges with your finger. Place a tablespoon or so of the mushroom filling in the center, and fold the square over into a triangle, pressing to seal the wet edges. Place it on a baking sheet that has been sprayed with nonstick spray or covered in parchment paper/a silicone mat. Repeat until you run out of squares or filling, whichever happens first. You can freeze any remaining pastry bits, and if you have a significant amount of mushroom filling left, it tastes delightful in a quiche. If you only have a few bites left, I recommend eating it when no one is looking. OM NOM NOM.
Once your triangles are arranges on the baking sheet (they can be fairly close together -- they will expand during cooking, but this expansion will be primarily upwards), give every one a good poke or two with the tip of a knife, to allow a vent for steam.
Bake for about 20 minutes. Depending on how close they are to the heat source and your particular oven, they may need as little as 15 minutes or as much as 25. Check on them at 15 -- you will know they are done when they are puffy and golden.