In a small bowl, whisk together flour, almonds, and ground cookies; set aside.
Place butter in the bowl of an electric mixer. Sprinkle over confectioners' sugar and toss, using your hands, until butter is fully coated. Attach bowl to mixer fitted with paddle attachment and beat on medium speed until butter and sugar are well combined.
Scrape down sides of bowl, add egg yolk, and continue beating until combined. Reduce speed to medium-low and slowly add the flour mixture; beat until well combined. Scrape down sides of bowl and add heavy cream and amaretto; beat until well combined. Form dough into a large ball using your hands. Wrap with plastic wrap and refrigerate 3 hours.
Lightly flour a work surface. Turn dough out onto floured work surface and cut into 8 pieces. Gently knead each piece of dough into a smooth disc, using a spatula to turn dough, as it will be sticky. Add more flour to work surface if necessary. Cover each piece with plastic wrap and refrigerate dough until chilled, about 10 minutes.
Using a rolling pin, roll each piece of dough into a 6-inch round, about 1/8-inch thick. Transfer each round to a 4-inch tart pan with a removable bottom and gently press into tart pan. Roll a rolling pin over each tart shell, pressing lightly to trim any excess dough; discard.
Place tart pans on a baking sheet and gently prick the bottom of each tart pan with a fork; transfer baking sheet to refrigerator and chill 30 minutes.
Meanwhile, preheat oven to 375 degrees. Transfer baking sheet to oven and bake tart shells until golden brown, about 15 minutes, rotating baking sheet halfway through baking. Remove from oven and let cook completely.