1 stick (8 tbsp) unsalted butter, at room temp and cut in pieces
fresh thyme sprigs or mint leaves
Preheat oven to 350F
Place the gingersnap cookies in the bowl of a food processor and process until they are finely ground. You should have about 2 cups. Add the walnuts and sugar; pulse to combine. Add the butter and pulse briefly again until everything is mixed together.
Pat the crust into a deep 9-inch pie plate, and up the sides. Bake for 10-15 minutes, until firm and slightly darkened. Set aside to cool. Note: Crust can be baked 1 day ahead. Store tightly wrapped at room temperature.
Put the cranberries, 2 cups of the sugar, and ½ cup water to a simmer in a large saucepan over medium heat. Lower the heat and simmer the cranberries, uncovered, for about 15 minutes until they’ve burst, most of the liquid evaporates and the mixture is quite thick. Let cool slightly and then puree in a blender until completely smooth.
Whisk the puree, the eggs, yolks, salt, lemon juice and 1 cup sugar together in a heatproof bowl set over a saucepan of simmering water (bowl should not touch the water, we are creating a double broiler here). Cook, stirring constantly, and scraping down the sides of the bowl often, until the curds thickens as spatula, about 10 minutes. Let cool slightly. Push the curd through a mesh strainer, using the back of a spoon to get it all through.
Drop the room temperature butter in, bit by bit, into the strained curd, while you stir to melt it.
Pour the curd into the piecrust and smooth out evenly. Chill the pie until it is firm, about 2 hours or so.
Decorate with sugared cranberries and thyme if you like.