Step 1Remove the zest from the oranges: Run a zester from the top to bottom of the orange, cutting the zest into thin strips (avoid the pith). Repeat with the remaining fruit. Reserve fruit for another use.
Step 2In a medium, heavy saucepan, cook the water and sugar over medium heat. Bring to a boil, stirring, until the sugar dissolves. Add the zest, lower the heat to medium-low, and cook at a gentle simmer until the zest strips become tender and semi-translucent, about 30 minutes.
Step 3Remove from the heat and pour into a heat-proof container. Cool completely, then store the zest in the cooking syrup in an airtight container in the refrigerator for up to 1 month. You should have about one-half cup (3 ounces) of candied zest.
Step 1Peel the quince, slice it in half, remove the core and cut the fruit crosswise into one-fourth-inch slices.
Step 2In a medium, heavy saucepan, combine the water and sugar over medium heat, stirring with a spoon, until the sugar dissolves. Add the fruit, reduce the heat to medium-low, and cook at a gentle simmer until the fruit is semi-translucent, about 45 minutes.
Step 3Remove from the heat and pour into a heat-proof container. Cool, then store the fruit in the cooking syrup in an airtight container in the refrigerator. You'll have about 1 cup (8 ounces) of fruit.
Step 1Heat the oven to 325 degrees. Butter a 10-inch springform pan with 2- or 3-inch sides, line with parchment paper, and butter the parchment, making sure to butter the sides of the pan well.
Step 2In a large mixing bowl, combine the candied quince and orange zest, dates, currants, orange and lemon zest, and all of the nuts. Sift together the flour, cocoa powder, cinnamon, nutmeg, coriander, pepper and cloves over the fruits and nuts. Mix well. Set aside.
Step 3In a deep, heavy saucepan, combine the honey and granulated sugar over medium-high heat. Stir gently with a wooden spoon from time to time to make sure that no sugar is sticking to the bottom of the pan. Bring to a boil and cook until the mixture registers 250 degrees on a thermometer, about 3 minutes. The mixture will be frothy and boiling rapidly.
Step 4Remove from the heat and immediately pour over the fruit-and-flour mixture in the bowl. Stir with a wooden spoon to incorporate the syrup thoroughly with the other ingredients. The mixture may seem dry at first, but it will come together once it is well mixed. (If you have rubber gloves, it is easier to mix with your hands than with a spoon.) Work quickly at this point; the longer the mixture sits, the firmer it becomes.
Step 5Transfer the mixture to the prepared springform pan and smooth the top with a rubber spatula dipped in water. Bake until the top is slightly puffed and looks like a brownie, about 1 hour. Cool in the pan on a wire rack for 30 minutes. Run a knife around the edge to loosen and turn out of the pan and cool completely.
Step 6With a fine-mesh sieve, sift the powdered sugar over the top, bottom and sides of the panforte. Lightly tap it over the counter to shake off excess sugar. It will keep, well wrapped, in a cool, dry place for up to 2 weeks, or indefinitely in the refrigerator. To serve, slice into quarter- to half-inch slices.