Make the churros: Combine 2 cups of the sugar with 2 tablespoons of the cinnamon, 2 teaspoons of the ground ginger, 2 teaspoons of the allspice, 1 1/2 teaspoons of the nutmeg and 1 1/2 teaspoons of the cloves in a baking dish. Set the spiced sugar mixture aside.
If using espresso, add it to a liquid measuring cup then add enough water to yield 1 cup of liquid. Alternatively, use 1 cup of coffee. Place in a medium saucepan over medium heat. Add the milk, butter, salt, the remaining 2 tablespoons sugar, 1 tablespoon ground cinnamon, 1 teaspoon ground ginger, 1 teaspoon allspice, 1/2 teaspoon nutmeg and 1/2 teaspoon cloves. Bring to a gentle boil, stirring.
When bubbles start to form at the edge of the saucepan, add the flour and stir continuously over the heat until the flour is absorbed and the dough pulls away from the sides of the saucepan, 1 to 2 minutes.
Place the dough in a stand mixer fitted with the paddle attachment and mix at low speed until the dough is cool, 3 to 4 minutes.
Add 1 egg, mix at low speed until well incorporated then mix in 1/4 cup of the pumpkin puree. Repeat twice more with the remaining 2 eggs and 1/2 cup of the pumpkin puree, mixing after each addition, until well incorporated.
Heat 1 1/2 inches oil to 350 degrees F in a large, wide saucepan over medium heat.
Fit a pastry bag with a star tip then fill three-quarters of the way with the dough. Working in batches, pipe long churros into the oil, using kitchen shears to cut the ends. Fry until golden brown and crispy, 2 to 3 minutes per side. Remove the churros from the oil with a pair of tongs, shaking off any excess oil and roll them in the spiced sugar mixture.
Make the tangy whipped cream: Combine the heavy cream with the confectioners' sugar and vanilla extract in a stand mixer fitted with the whisk attachment. Whip at medium speed until soft peaks form. Remove from the machine and finish whipping the cream by hand until medium-stiff peaks form. Fold in the sour cream and a pinch of salt. Serve with the churros and enjoy.
Churros are best served right away but if you must make them in advance, reheat them in a 350 degree F oven until warm and crispy, 3 to 5 minutes.