Dissolve alum in 1/2 cup water. Keep aside.
Dissolve lime in 1 litre water, strain with a clean cloth, twice if required.
Peel pumpkin, dicard seeds, mushy centre.
Cut into 1"x2"x1" rectangular blocks or as desired.
Prick all over with a metal skewer or fork.
Put pieces in lime water. Soak for 30-35 minutes.
Drain, wash under clean running water for 2-3 minutes.
Put in a bowl, sprinkle alum water, shake to coat all pieces evenly.
Drain, boil pieces in a large heavy pan, till a little soft and exuding water.
Make a syrup of sugar and water, till 2 1/2 thread consistency (refer syrup method)
Put drained pumpkin pieces in syrup, boil till syrup becomes thick again.
Keep covered with a mesh, overnight.
Drain, boil syrup again till thick, add pieces, reboil for 3-4 minutes.
Drain out excess syrup, sprinkle essence and rose water.
Cool completely, refrigerate.