Thaw the puff pastry fully in the refrigerator before beginning.
Pour the lemon juice into a medium bowl with a cup of cold water. Combine the brown sugar with the cinnamon and mix together. Spray a muffin pan with non-stick spray.
Core the apples and cut them in half lengthwise. Place the flat side down on the chopping board and from the bottom of the apple to the top, start slicing into very thin slices, as thin as you can get them. You can use a mandolin if you prefer.
Place the apple slices into the bowl of lemon water and make sure they are coated to prevent browning. Set aside.
Unpackage the puff pastry and place it on a lightly floured work surface. Roll it out to make it thinner and larger by about an inch in each direction.
Cut the puff pastry into 6 even strips and space them apart slightly on your work surface.
Mix the jam with a splash of hot water to loosen it up, then use a pastry brush to cover each of the strips in a thin layer of jam.
Sprinkle each strip generously with the cinnamon brown sugar.
Microwave the bowl of apples for 2 minutes to soften them. Then drain the excess water. If they are too hot to touch, let them sit for a minute to cool off, but don't let them cool completely.
Place apple slices along the top edge of one of the pastry strips so they are just slightly sticking out over the edge. Line them up so that the next apple starts halfway across the last apple, until you reach the end of the strip (see pictures in the post above). I recommend placing the apple slices and rolling the roses from start to finish for each strip, one at a time.
Fold the bottom of the pastry strip up on itself, as if you are tucking the apples into bed.
Brush the top of the strip with a little more jam to help it stick, and then carefully start rolling up the pastry from one end to the other until you have a perfect little rose shape.
Place the puff pastry rose inside a muffin pan cavity. Repeat with all the strips.
Once all 6 roses are formed, place them in the refrigerator to chill while you preheat the oven to 400°F / 200°C.
Bake the roses on the middle rack for 40-45 minutes. If the apples start to brown, you can tent them with some kitchen foil, though I personally love the look of the slightly charred edges!
Once done, the pastry should be golden brown. Remove them from the oven and run a sharp knife around the edge of the pan if needed. Transfer the roses to a cooling rack immediately to prevent them from sticking to the pan or going soggy.
Optional: If you want to, you can melt a little more jam in the microwave and brush it onto the top of the apples as a shiny glaze.
Notes
You may need more apples depending on how thick you cut your slices and how big the apples are. Puff pastry typically comes in packs of two rolls. This recipe will only use one roll to make 6 apple roses, you can easily double the recipe to make 12 roses. See the post above for step-by-step process shots of how to make apple roses.