This silky frozen mousse flavored with espresso and amaretto has a sweet-and-tart cherry topping.
For semifreddo: Line a 4-by-8-inch loaf pan with plastic wrap; set aside. While the espresso is still hot, add all but 2 tablespoons of sugar and stir until dissolved. Cool.
Set a fine-mesh strainer over a large bowl and with a wooden spoon or a spatula, push ricotta through. Add half of the espresso mixture, amaretto, lemon zest, and salt, and whisk until well combined.
Combine egg yolks and remaining espresso in a stainless-steel bowl and whisk until eggs are foamy. Set the bowl over, not in, a pan of simmering water, being careful not to let the bottom of the bowl touch the water. Continue whisking until the mixture is foamy, light colored, and tripled in bulk. This could take up to 10 minutes. If cooking too quickly, turn heat off and work over the hot water. Cool to room temperature.
Meanwhile, with an electric mixer, whip egg whites until foamy. Add remaining 2 tablespoons sugar and whip to stiff peaks.
Stir 1/4 cup of cooled yolk mixture into the ricotta mixture to lighten. Fold in the remaining yolk mixture and 1/3 of the whites. Gently fold in remaining egg whites. Spoon mixture into prepared loaf pan and gently smooth top. Crumble the amaretti cookies and spread over the top. Cover with plastic wrap and freeze at least 24 hours.
For the fruit: Combine kirsch and sugar in a medium stainless-steel saucepan. Place over low heat and stir until sugar dissolves, about 1 minute. Add remaining ingredients and mix well. Remove from heat and let sit for at least 2 hours or overnight at room temperature.
To serve: Remove semifreddo from the freezer 20 minutes before serving. Uncover top; invert semifreddo onto a serving platter and remove plastic wrap. Cut into 1-inch slices, spoon on cherries, and serve.
Semifreddo is Italian for "half cold." For the proper texture, the egg yolks must be beaten over enough heat so they emulsify, but not so much that they start to scramble.