I love limoncello (here's a great recipe for it), but what can you possibly serve with it? When a friend offered to bring some to dinner, it inspired this little research project, which yielded some surprising results. Besides just about any kind of shortbread and / or dark chocolate, other citrus flavors actually work quite well...
To make the cake, preheat the oven to 300ºF. Butter a 4-by-8-inch loaf pan. Then, using a sifter or a fine-mesh strainer, dust it with flour, tapping out the excess.
In a food processor, combine the pistachios and almonds and pulse until finely ground. Set aside.
Combine the butter and sugar in the bowl of a stand mixer. Grate the zest from the lemons directly into the bowl. Fit the mixer with the paddle attachment and beat on medium speed for about 2 minutes, or until smooth and creamy. Mix in the vanilla just until incorporated. On low speed, gradually add the nuts and mix just until incorporated. Then add the eggs, one at a time, mixing after each addition just until incorporated. Stir in the flour and salt and mix just until incorporated.
Spoon the batter into the prepared loaf pan. Bake until a skewer inserted in the middle comes out clean, about 45 minutes. Let cool in the pan on a wire rack for 10 minutes. Then, run a pairing knife around the inside of the pan to loosen the cake sides, invert the cake onto a plate, and lift off the pan. At this point, the cake can be served warm or allowed to cool completely before being sliced and reheated.
Place 4 or 5 orange slices on each plate and drizzle generously with the marmalade syrup. Place the warm pieces of cake next to the orange slices and top with a dollop of yogurt and a few pistachios. Serve immediately.