Preheat your oven to 350°F (180°C).

Butter and line a 9 inch (23 cm) or a tall 8 inch (20 cm) cake pan* with a parchment round.

In a medium mixing bowl, whisk together the flour, almond flour, baking powder, baking soda, and salt. Break up any clumps with your whisk, or sift it if you’re having trouble working out all the lumps. Set aside.

Place the butter, sugar, citrus zest, and cardamom in the bowl of a stand mixer fitted with the paddle attachment (or use a large mixing bowl with hand-beaters). Beat at medium-high speed for about 2 minutes, until fluffier and completely homogenous.

Crack the eggs into a container that has a pour spout. Run the mixer at medium-high speed and add the eggs 1 at a time with the mixer running. Wait for each egg to completely incorporate before adding the next one. Scrape down the bottom and sides of the mixing bowl and beat again to make sure it’s fully incorporated.

Add the buttermilk and rosewater and mix together just to incorporate. Scrape the bottom and sides of the bowl again to make sure it’s mixed evenly.

Add the dry ingredients to the wet ingredients, turn the mixer to low, and let it mix just until smoothly incorporated. Do not overmix. Scrape the bottom of the bowl and give it just one or two folds by hand to make sure it’s evenly incorporated.

Pour into the parchment-lined pan and smooth out the top.

Bake for about 50 minutes, until a toothpick inserted in the center comes out cleanly.

Carefully trace around the edges of the pan with a thin knife. Flip it onto a cooling rack. Let it cool for at least 1 hour before decorating.

While your cake cools, make the icing by whisking together the powdered sugar, rosewater, and citrus juice until completely smooth.

Place your cooled cake bottom-side-up on a plate or cake stand. If your cake domed (usually from not measuring with weight and using too much flour), first shave off the top so it sits levelly, then place it bottom-side-up.

Pour the icing on the top, then smooth it out to the edges using a knife or offset spatula. Sprinkle with pistachios and rose petals before it sets.

Serve immediately, store leftovers at room temperature for a day or two, and store anything you won’t eat in the near future in the freezer ASAP (do not refrigerate or it will stale).