01 -
Heat oven to 425°F (220°C). Lightly spray 9 (of the 12) cups in the muffin tin with oil.
02 -
Place diced apples, butter, brown sugar and cinnamon in medium skillet. Heat to medium high. Stir 2-3 minutes so that apples begin to release juices. Cover, lower to medium heat, and cook 10 minutes. Uncover, and cook 2-3 more minutes until all liquid evaporates.
03 -
Unfold puff pastry sheet onto a lightly floured surface. Use a rolling pin to roll it to ~11x11 inches/ 28 x 28 cm (making it a little bigger on all sides). Alternatively, stretch it out a bit by hand. Cut into 9 squares with a sharp knife or pizza cutter.
04 -
Place each square in a muffin tin cup (stretch it out a tiny bit before placing it in the cup). Press down so that the dough touches the bottom and the corners hang over the top. Repeat with all 9 puff pastry squares.
05 -
Fill each puff pastry cup with apple mixture about 3/4 full. You will use about 2 1/2-3 tablespoons for each cup. To cover each mini pie with puff pastry: fold the two overhanging corners facing each other towards the middle. Pinch. Then fold the other two corners towards the middle and pinch. Leave a few air vents. Brush the tops with egg wash using a pastry brush to create a golden brown finish (optional - pies will just be paler without it).
06 -
Bake pies in middle rack of oven for 20-25 minutes or until golden brown with a flaky crust. Transfer the pies to a cooling rack (gently scoop them out with a soup spoon) to cool for 8-10 minutes.
07 -
Place powdered sugar in a small fine mesh sieve and shake it gently over each pie to distribute over the tops. If you don't have a sieve, just use your fingers and sprinkle from 10 inches/25 cm above.