Clean the pumpkin, bake it in the oven or boil until soft, blend in a blender. Wipe the pumpkin puree through a sieve. In a bowl or pot combine the pumpkin puree, egg and yolks, sugar, lemon zest and cinnamon. Mix well with a whisk.

Put on medium heat, continuously interfere with a whisk until the cream starts to thicken (mine took about 1.5-2 minutes). Reduce the heat to minimum and cook, stirring constantly, for another 8-9 minutes until the cream thickens well.

Remove from heat, give a little cool, add the pieces of butter.

Mix well so the butter is completely melted and the cream is smooth, silky consistency. To shift the cream in a convenient bowl and put into the fridge for a couple of hours.