Prepare the ingredients and loaf pan

1. Remove the eggs and heavy cream from the refrigerator about 30 minutes before baking. Room-temperature ingredients combine more evenly and help produce a smoother batter.

2. Preheat the oven to 400°F or 200°C using conventional heat. If using a convection or fan-assisted oven, reduce the temperature slightly.

3. Line a 9 x 5-inch or 22 to 24 cm loaf pan with parchment paper. Leave some paper extending over the two long sides so the baked cake can be lifted out easily.

4. Melt the butter over low heat or in short intervals in the microwave. Set it aside until it is still liquid but no longer hot.

5. Stir the pistachio paste thoroughly before measuring it, especially if its natural oils have separated in the jar.

Make the pistachio cake batter

6. Break the eggs into a large mixing bowl and add the granulated sugar.

7. Beat the eggs and sugar with an electric mixer for 3 to 4 minutes. The mixture should become pale, airy, and slightly thicker.

8. Warm the heavy cream very gently. It should be barely lukewarm, not hot enough to cook the eggs or deflate the mixture.

9. Pour the cream slowly into the whipped eggs while mixing at low speed.

10. Add the pistachio paste and mix until it is fully incorporated. Scrape the bottom and sides of the bowl to make sure no thick streaks of paste remain.

11. In a separate bowl, whisk the flour and baking powder together. This distributes the leavening evenly throughout the flour.

12. Sift about one-third of the flour mixture over the wet ingredients. Fold it in gently with a spatula.

13. Add the remaining flour in two additions, folding after each one. Stop mixing as soon as no dry flour remains; overmixing can make the finished cake dense.

14. Pour in the melted and slightly cooled butter in a thin stream. Fold gently until the batter is smooth, evenly colored, and slightly glossy.

15. Scrape across the bottom of the bowl several times to ensure that the melted butter has not collected underneath the batter.

Fill and bake the cake

16. Transfer the batter to the prepared loaf pan. Smooth the surface with the back of a spoon or a small spatula.

17. Tap the pan gently against the counter once or twice to release any unusually large air pockets.

18. Scatter the chopped pistachios evenly over the top. For a more controlled split, draw a thin line of softened butter lengthwise down the center of the batter.

19. Place the pan in the center of the preheated oven and bake at 400°F or 200°C for 5 minutes.

20. Without opening the oven or removing the pan, reduce the temperature to 310°F or 155°C.

21. Continue baking for approximately 35 minutes. Begin checking the cake a few minutes early because the baking time varies with the pan material and the accuracy of the oven.

22. Insert a thin skewer or knife into the thickest part of the loaf. The cake is ready when it comes out clean or with a few dry crumbs, but no wet batter.

23. If the surface is sufficiently browned before the center is baked, cover the loaf loosely with aluminum foil and continue baking for a few more minutes.

Cool and serve

24. Remove the pan from the oven and let the cake rest inside it for approximately 5 minutes.

25. Lift the cake out using the parchment-paper overhang and transfer it to a wire rack. Carefully peel away the paper so moisture does not collect around the sides.

26. Let the pistachio cake cool before slicing. Its crumb is delicate while hot and becomes more stable as it cools.

27. Cut the loaf into 10 slices and serve it plain or with fresh raspberries, a tart berry sauce, coffee, or tea.