Preheat oven to 350 F.
Grease and flour an 8-cup ring or bundt pan.
In the bowl of a food mixer, beat the butter and sugar on medium-high speed until lighter in colour and slightly increased in volume, about 4 minutes. Reduce the speed to medium and add eggs, one at a time, beating each addition until fully incorporated.
Alternate dry ingredients (all-purpose flour, almond flour, baking powder, sea salt) and wet ingredients (buttermilk and rosewater) into creamed mixture, beginning and ending with dry ingredients. Mix until well combined or finish gently by hand.
Transfer batter to pan and bake for 30-35 minutes. Oven temperatures can vary, so check with a toothpick to make sure it comes out clean.
Invert from pan once cake has cooled. Dust with icing sugar and adorn with rose petals.