Orange and spices is a classic flavor combination for fall and winter, when citrus is in season and spices are dried, ground and preserved for cold weather. We embrace that approach in this loaf cake, whose decadence goes off the charts with a sweet ginger buttercream.
Preheat oven to 350°F. Line a 9-inch x 5-inch loaf pan with a parchment paper sling and set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, ginger, and cloves.
Place butter, sugar and orange zest in the bowl of a stand mixer fitted with a paddle attachment. Cream on medium speed until light and fluffy, about 3 minutes. Add eggs, one at a time, beating well after each addition.
Mix in orange juice and molasses. With mixer running on low speed, add the flour mixture alternately with the buttermilk, starting and ending with the flour. Mix until just combined.
Pour batter into prepared pan and smooth the top. Bake for 50-60 minutes, or until a toothpick inserted in the center comes out clean. Let cool in pan for 10 minutes, then carefully lift cake out of pan using the parchment paper sling. Cool completely on a wire rack.
Ginger Buttercream
Remove butter from the fridge and let it soften for 10 minutes.
Place butter in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed to soften, about 30 seconds. Add all of the sifted powdered sugar and ground ginger, attach splash guard, and mix on low speed until it just comes together, about 3 minutes. Mixture will look very powdery at first. Scrape down sides and bottom of bowl, and mix again.
Turn mixer on high, immediately add vanilla extract and hot water, and mix until just combined and smooth, about 20 seconds. Transfer to a piping bag and decorate loaf cake as desired. Garnish with candied ginger and orange peel.