Step 1In a heavy pot, combine the milk, butter, salt and sugar over medium heat. When the butter has melted and the mixture comes to a simmer, add the flour. Vigorously mix to form a dough, and continue stirring, using a wooden spoon until the dough forms a film at the bottom of the pot that turns a golden-brown.
Step 2Transfer the dough to a mixer bowl and mix with a paddle for 10 minutes at medium speed, until the mixer bowl is cool to the touch.
Step 3When the dough is room temperature, with the mixer running, add 2 eggs. Once the eggs are fully incorporated, add the remaining 2 eggs. Remove the dough from the mixer to a container. Cover the surface of the dough with plastic wrap and refrigerate. The dough can be made a day or two in advance.
Step 1Slice the foie gras into 2-inch pieces.
Step 2Heat a sauté pan over high heat. Sear each piece of foie gras on all sides. The foie gras will give off about 1/2 cup of fat.
Step 3Remove the foie gras to a plate to cool, reserving the fat in a bowl. Meanwhile, place the lucuma purée and condensed milk in a separate bowl.
Step 4When the foie gras is cooled, purée the pieces in a blender with the purée, milk and foie gras fat (do this in two passes) until smooth. It should have the consistency of smooth peanut butter. Place the filling, you’ll have about 11/2 cups, in a shallow container or baking dish, cover with plastic wrap and freeze.
Step 1In a heavy, medium pot, combine the cranberries, water and sugar over medium heat. Cook, stirring frequently, until the cranberries have doubled in size and soaked up the water, about 5 minutes. Make sure the sugar is dissolved before removing from heat.
Step 2Carefully transfer the hot cranberries to a blender and purée until smooth. Transfer the sauce to a bowl and stir in the lemon juice and pisco. Set aside to cool. (This can be made a few days in advance. It makes about 2 cups.)
Step 1Line a rimmed baking sheet with wax paper.
Step 2Remove the foie gras filling from the freezer. Warm a small melon ball scoop using hot water, then carefully scoop the filling with the melon baller, placing the foie gras balls on the prepared baking sheet. Continue until the sheet is filled or you have as many as you wish. Place the baking sheet in the freezer.
Step 3Dust a separate baking sheet with flour. Using a very small (1-ounce) ice cream scoop, scoop the churro dough into as many balls as you have fillings.
Step 4Using your thumb, press into a churro dough ball to make a crease. Place a frozen filling in the crease and pinch over dough, sealing the filling in the dough. Roll the dough in between your hands to form the dough into a ball. Continue with the dough and fillings.
Step 5Heat a large, heavy pot half-filled with oil until a thermometer inserted reads 325 degrees.
Step 6Slowly add the churros, a few at a time, to the oil using a slotted spoon. Fry the churros until golden-brown and firm on the outside, about two minutes. Drain them on a dry paper towel, then, while they’re still warm, toss them in the granulated sugar.
Step 7Serve the churros with the cranberry-pisco sauce.