A moist, rich cake combining crushed pistachios and swirls of Nutella throughout. Takes about 1 hour and 15 minutes including baking time. Perfect for intermediate bakers looking to create an impressive dessert with minimal effort.
Clear a clean workspace on your counter. Preheat your oven to 180°C (350°F). Grease a 9-inch round cake pan with butter, then dust lightly with flour, tapping out any excess. Set aside.
Shell the pistachios if they're not already shelled. Place 100g in a food processor and pulse until finely ground but not turned into paste. Set aside the remaining whole pistachios for decoration.
In a large mixing bowl, beat the softened butter and sugar together using an electric mixer on medium speed for 3-4 minutes until the mixture is pale, light, and fluffy.
Crack in one egg at a time, beating well after each addition. If the mixture starts to look curdled, add a tablespoon of flour. Add the vanilla extract and mix until combined.
In a separate medium bowl, whisk together the flour, baking powder, salt, and the ground pistachios you prepared earlier until evenly mixed.
Add half of the dry ingredients to the butter mixture and gently fold with a spatula. Pour in half the milk and fold again. Repeat with remaining dry ingredients and milk, mixing just until no flour streaks remain. Don't overmix.
Place the Nutella in a small microwave-safe bowl and microwave for 15-20 seconds until it's slightly runny and easier to swirl. Stir gently.
Pour half of the cake batter into your prepared pan and spread evenly. Drop half the warmed Nutella in dollops across the surface. Add the remaining batter on top, then add the rest of the Nutella in dollops. Use a butter knife to create swirls by gently dragging it through the batter in a figure-8 motion.
Roughly chop the remaining whole pistachios and sprinkle them over the top of the cake batter for decoration and extra crunch.
Place the cake pan in the preheated oven on the middle rack. Bake for 45-50 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs (not wet batter). The top should be golden brown and spring back when lightly pressed.
Remove the cake from the oven and let it cool in the pan for 15 minutes. Then run a knife around the edges and carefully turn it out onto a wire cooling rack. Let it cool completely before slicing, about 30-40 minutes.
Once completely cooled, slice and serve. Store any leftover cake in an airtight container at room temperature for up to 3 days, or refrigerate for up to 5 days.