To Make the Custard Filling
Quickly make sure that the caramel coats the bottom and sides of the mold before it hardens.To prepare the custard, put the milk, sugar, pumpkin and vanilla into a saucepan and heat over a medium heat until simmering. Cook until all of the sugar is dissolved and the mixture is evenly heated. Remove the mixture from the heat and let it cool for about 10 minutes, stirring every minute or two. Preheat your oven to 325°F.Lightly beat the eggs in a large bowl. Making sure that the milk and pumpkin mixture is sufficiently cool (so that it won’t scramble the eggs), whisk in this mixture little by little, until all is incorporated. Pour the custard mixture over the caramel. Place the flan mold/pan into a large baking pan. Boil enough water to fill the baking pan halfway (you have to cook the flan in a bain marie). Bake the flan for about one hour in a preheated oven at 325°F. Remove the mold from the pan of water and allow it to cool completely. Cover with plastic wrap and let chill in the fridge overnight (or for at least 4 hours).