Spiced with ginger, cinnamon, nutmeg and cloves, this Autumn-inspired Harvest Cake is gently sweet and rich with butternut squash, apples and pears. Light and fluffy Maple Frosting, spiked with the lightest touch of dark rum, finishes the cake.
Heat the oven to 350 F, and line three 8-inch baking tins with parchment paper. Grease and flour the tins.
In a medium bowl, whisk the flour, cinnamon, ginger, nutmeg, cloves, baking powder, baking soda and sea salt together.
In a separate bowl, beat the eggs, maple sugar and 2 tablespoons dark rum together until thickened and fluffy, 3 to 5 minutes. Continue beating the eggs and sugar together while drizzling the oil into the bowl in a thin, steady stream.
Add one-third of the dry ingredients into the bowl, stirring until they're fully absorbed into the egg mixture. Then stir in half the kefir. Add another one-third of the dry ingredients to the bowl, stirring until fully incorporated, and then stir in the remaining kefir. Stir the remaining flour mixture into the bowl, and make sure it’s fully incorporated into the batter. Fold the butternut squash, apple, pears and pecans into the batter.
Distribute the batter evenly among the prepared cake tins, and bake for 30 to 35 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow the cakes to cool for five minutes in the pan, and then turn them out onto a wire rack to cool completely.
While the cakes cool, prepare the Maple Sugar Frosting.
In a double boiler, whisk the egg whites, maple sugar and salt together constantly until the sugar fully dissolves. Transfer the egg white mixture to the basin of stand mixer fitted with a balloon whisk. Whip the sweetened egg whites they form a glossy meringue and hold stiff peaks. Test the bottom of the mixing bowl, and when it has cooled to room temperature, whisk in the softened butter 1 tablespoon at a time at medium-low speed until the butter is fully incorporated. Whisk in the dark rum, and continue whisking until the frosting is smooth, light and glossy.
Frost the cakes when they are completely cooled, and serve them at room temperature.
Variations. You can substitute regular all-purpose flour or sprouted whole grain flour for the einkorn flour.