• Preheat oven to 350°F.
• Coat a 9" cake pan with nonstick spray and line base with a parchment paper round.
• Whisk flour, baking powder, baking soda, salt, cinnamon, ginger and nutmeg in a large bowl to combine.
• Combine sugars, oil, honey, egg, egg yolk and vanilla in the bowl of an electric mixer.
• Beat mixture until pale and thickened, about 4 minutes.
• Reduce speed to medium-low and gradually pour in orange juice and buttermilk. Beat until frothy, about 2 minutes.
• Reduce speed to low and gradually add dry ingredients; beat just until smooth. The mixture will be thin, like pancake batter.
• Pour into prepared pan and bake until cake is golden brown and center springs back when gently pressed (a cake tester will not come out clean), 50–55 minutes.
• Transfer to a wire rack and let cool in pan.
• Run a knife around edges of cake to loosen and invert onto rack; let cool completely.

For the Frosting

• Using a hand mixer, beat cream cheese and butter in a medium bowl until smooth. Add powdered sugar, lemon zest, salt and vanilla. Beat on low speed until mixture is very light and smooth, scraping down sides of bowl.
• Pile frosting on top of cooled cake and spread to edges.
• Decorate with nasturtium flowers and leaves (or any edible flowers), rosemary sprigs, variegated sage and pomegranate seeds.