Combine cinnamon, nutmeg, allspice and orange zest with pumpkin puree.
In a sauce pan, start to heat the milk and cream, but do not bring to a boil.
Whisk together the eggs and egg yolks in a large bowl. Once the milk is warm, remove from heat slowly add to egg mixture, whisking continuously.
Once incorporated, add the brown sugar, pinch of salt and vanilla and whisk until dissolved.
Pour through a mesh strainer into another container that can hold the pumpkin puree as well and be refrigerated.
Whisk to combine the spiced pumpkin puree with the egg mixture and chill at least 3 hours.
Add 1 cup sugar and then 1/4 cup water to a sauce pan. Heat until the sugar dissolves then add lemon juice.
Continue to heat, swirling the pan to cook evenly without stirring.
Once mixture is a deep amber color, remove from heat and slowly add the remaining 1/4 cup water. The caramel mixture will bubble up. Using a heatproof spoon, stir to combine.
Pour the caramel into the ramekins, allow to cool and chill until caramel has set.
Divide the chilled custard into the ramekins and place in large roasting pan with at least 2" sides.
Pour enough warm water into the pan to reach halfway up the ramekins and cover tightly with aluminum foil.
Bake at 325°F for 30 to 35 minutes or until the edges are clearly set, but center slightly liquid.
Remove from roasting pan and allow to cool on wire racks.
Once cooled, cover and return to refrigerator to chill.
When ready to serve, invert onto serving plate, drizzle any extra caramel over the flan and sprinkle with pepitas.
