Step 1Heat the oven to 350 degrees. Butter and flour a nonstick 9-inch-square baking pan, tapping the pan to remove excess flour. Sift together the flour, baking powder and salt into a medium bowl.
Step 2In the bowl of a stand mixer, or in a large bowl using an electric mixer, beat the butter until smooth. Add the sugar and beat until the mixture is light and fluffy, 3 to 5 minutes. Beat in the honey. Add the eggs, one at a time, beating well until fully incorporated. After you add the third egg, the batter will look separated; it will come together when you add the flour. Beat in 2 tablespoons of the flour mixture at low speed.
Step 3Beat in the lemon and orange zests and vanilla. With a wooden spoon, stir in the remaining flour mixture in 3 portions; the batter will be thick. Stir in the figs, raisins and chopped walnuts.
Step 4Spread the batter evenly in the prepared pan, using a spatula if needed. Bake until the cake is golden and a cake tester or a toothpick inserted in the center comes out clean, about 30 minutes. Remove the pan from the oven but keep the oven heated.
Step 5Transfer the pan to a wire rack to cool for 15 minutes.
Step 6While the cake is cooling, make the garnish: Spread the walnut pieces onto a rimmed baking sheet and toast in the oven (still at 350 degrees) until they are fragrant and slightly darker in color, about 5 minutes. Transfer the walnuts to a plate to cool, and turn off the oven. Chop the walnuts finely.
Step 7After 15 minutes, remove the cake from the pan. Turn the cake out onto the rack, and cool completely before glazing it.
Step 8Make the glaze: Heat the preserves with 2 tablespoons water in a small saucepan over low heat, stirring, until the mixture just begins to bubble, about 10 minutes. Strain the mixture, pressing on the fruit pieces. You will need one-half cup glaze.
Step 9The glaze should have the fluidity of warm maple syrup; if it is too thick, heat it briefly in the saucepan with 1 or 2 tablespoons more water. If it is too thin, simmer it over medium-low heat, stirring often, for 2 or 3 minutes to reduce and thicken it. Pour the finished glaze over the cake and brush it evenly over the top. Sprinkle the cake with the chopped toasted walnuts.
Step 10Set the cake aside for about 30 minutes before serving. To serve, cut it in square or oblong pieces.