1/2 navel orange, zest grated
1/2 green apple, cored and peeled
8 ounces honey
1 cup minus 2 tablespoons sugar
1/4 cup vegetable oil
3 eggs, separated
2 1/2 cups flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1/2 teaspoon cinnamon
1/2 teaspoon each nutmeg, ginger and allspice
6 tablespoons strong coffee
2 tablespoons Scotch whiskey
Pinch cream of tartar
1. Preheat the oven to 350˚F. Line a 9-by-13-inch pan with parchment paper. Using the grater disk of a food processor (or the coarse side of a box grater) grate together the orange pulp and apple. Add the orange zest to the fruit and set aside.
2. In a large mixing bowl, beat together the honey and all but 1 tablespoon of the sugar. Whisk in the oil, then the egg yolks, and beat until well combined.
3. In a large bowl, sift together the dry ingredients. In a small bowl, combine the coffee and whiskey.
4. In a clean bowl of an electric mixer, beat the egg whites with the remaining tablespoon of sugar and the cream of tartar at medium speed until they form soft peaks.
5. Add the dry ingredients to the honey mixture in thirds, alternating with half the whiskey-coffee mixture until smooth. Beat in the orange and apple mixture, then gently fold in the egg whites.
6. Scrape the batter into the pan, put it in the oven and reduce the oven temperature to 300˚F. Bake until a tester inserted into the center of the cake comes out with a few moist crumbs on it (not batter), about 1 hour. Cool in the pan on a wire rack. Can be frozen, well-wrapped, for up to 1 month.