In a small saucepan, bring the honey, sugar, and water to a boil over medium high heat. Reduce heat to low and simmer for 10 minutes, then remove from heat and allow to cool until warm, then stir in orange blossom water. You can use more or less of the orange blossom water in the recipe depending on the strength of the brand you have. I used Nielsen Massey brand, but the flavor concentration can vary depending on the brand you have, so giving the syrup a taste and adjusting to your personal flavor preference is a good idea.
Preheat the oven to 350 degrees Fahrenheit. Grease (3) 8-inch cake pans and line the bottoms with parchment paper. Set aside.
In a large bowl, mix together the flour, almond meal, baking powder, cardamom, baking soda, and salt. Set it aside.
In the bowl of an electric stand mixer fitted with the paddle attachment, beat together the butter and sugar at medium speed until smooth and fluffy, about 1 minute. Add the eggs, 1 at a time, waiting until the egg is fully incorporated into the batter before adding the next one. Add the honey and mix to combine.
With the mixer running at low speed, alternate between adding the flour mixture and the buttermilk in 4 increments until combined. Stir in the vanilla extract, orange blossom water, and orange zest. Evenly distribute the batter between the cake pans and place them in the oven. Bake until golden around edges, lightly golden on top, and a toothpick inserted into the center comes out clean, about 20 minutes.
Allow the cakes to cool in the pan for 10 minutes, then poke top the top of each cake 1 dozen times with a fork pour, and drizzle the syrup evenly over the three cakes. Allow the cakes to cool to room temperature and absorb the syrup, then flip them out onto a wire rack and allow them to continue to cool while you prepare the buttercream.
Place the shelled pistachios in a food processor and blend until creamy and smooth (like a thick peanut butter in texture), about 1 minute. Set the pistachio butter aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter at medium speed until utter until pale and smooth, about 1 minute. Add the pistachio butter and beat until incorporated. Then add the powdered sugar and beat at low speed until combined, then add the milk and salt and raise the speed to medium and beat until light and fluffy, about 2 to 4 minutes.
To assemble: layer and frost the cake with the pistachio buttercream. To create the round icing decorations around the top edge of the cake, use a pastry bag with a large round tip and follow the icing method in this video: https://www.youtube.com/watch?v=Sl24VWJZFMI
Sprinkle the finely chopped pistachios around the lowest inch of the icing around the bottom edge of the cake. Sprinkle any excess chopped pistachios on top, and serve.