Put the apple peel and cores in the muslin bag. Pour half cup of water into the saucepan with muslin bag and cook for 15 minutes or until the liquid is thick and pectin is formed.
Squeeze the muslin bag into the hot water to release pectin. Discard the solids, keep the liquid.
Dice the apples and add to the saucepan with berries and pectin liquid. Cook until softened.
Add sugar and cook until fully dissolved.
Stir in rose petals and rose water, then turn off the heat. Avoid over-stirring to prevent unset jam.