To prepare the pistachios and the crumble, heat the oven to 375F/190C. Move the pistachios to the bowl of a food processor; pulse 30 times. Remove one quarter of the pistachios from the processor, and set them aside. To the food processor, add the lemon zest, flour, and sugar; pulse 10 more times. Add the butter, and mix until everything just comes together, about 1 minute. Empty the pistachio shortbread onto a baking sheet; use your fingers to crumble and separate the "dough," so that it is spread out across the baking sheet, and is not too clumpy. Bake for 20 minutes, or until the shortbread crumbles are golden and aromatic. Allow the crumbles to cool completely, at least 30 minutes.
To make the raspberry drizzle, spoon the jam into a small bowl. Add 1 tablespoon water, and the rosewater is using, and stir until completely incorporated. Refrigerate until needed.
To begin the gelato/sorbetto cake, pack one third of the pistachio crumbles into the bottom of a 6-inch springform pan. Using a large spoon, add 1 pint of the pistachio gelato to the springform; use the back of the spoon to smooth the top. Add another third of the crumbles, and then repeat with 1 pint of the raspberry the sorbetto. Over the sorbetto, scatter 1/2 cup of the frozen raspberries and 1/2 the raspberry drizzle. Finish with the remaining pistachio crumbles. Cover with plastic wrap, and move the springform to the freezer for at least 2 hours, but up to overnight.
To finish the gelato/sorbetto cake, prepare a warm glass of water and an ice cream scoop. Working quickly, and alternating between the remaining pint of pistachio gelato and raspberry sorbetto, "decorate" the top of the cake with fat scoops. Drape the plastic back over the cake, and move it back to the freezer for another 3 hours, or up to overnight.
To serve the gelato/sorbetto cake, remove the cake from the freezer. Undo the springform, so that the cake stands alone. Decorate the top with the remaining raspberry drizzle, crushed pistachios, and remaining frozen raspberries. Slice and serve right away.
Cristina is a writer, cook, and day job real estate developer. She studied literature, holds an MFA in Fiction Writing, and completed the Basic Cuisine course at Le Cordon Bleu in Paris. She lives in Jersey City with her husband--a Frenchman she met in Spain--and their sweet black cat, Minou. Follow her writings, recipes, publications and photography at theroamingkitchen.com.