Make the dough: Whisk together nuts, flour, sugar, salt, and lime zest in a large bowl. Using your fingertips, work in butter until the largest pieces are the size of peas; make a well in center. Whisk yolk and egg in a small bowl, and pour into well. Gradually draw flour mixture into center, kneading until combined. Shape dough into a disk. Wrap in plastic, and refrigerate overnight (up to 3 days).
Start the filling: Place ricotta in a sieve lined with cheesecloth, and set over a bowl. Cover, and refrigerate overnight.
Prepare an ice-water bath; set aside. Whisk sugar, yolks, and eggs in a large heatproof bowl. Whisk in lime zest and juice. Set bowl over a pan of simmering water. Cook, whisking occasionally, until thick, about 30 minutes.
Remove from heat. Add butter, a few pieces at a time, whisking until smooth after each addition. Pour through a fine sieve into a bowl set in ice-water bath. Place plastic wrap directly on surface of lime curd. Let cool. Refrigerate overnight (up to 3 days).
Preheat oven to 325 degrees. Let dough come to room temperature; roll out on a lightly floured surface to 1/4 inch thick. Fit dough into a 10-by-3-inch springform pan, pressing and patching so that dough reaches 2 inches up sides of pan. Line with parchment; fill with pie weights or dried beans. Chill in freezer 15 minutes.
Bake crust 30 minutes. Remove pie weights and parchment. Bake until edge of crust is golden brown and inside is pale golden brown, 15 to 18 minutes. Let cool slightly on a wire rack. Remove sides from pan; and transfer crust to rack to cool completely.
Assemble tart: Spread 2 1/2 cups lime curd over crust. Put ricotta and mascarpone into the bowl of an electric mixer fitted with the whisk attachment. Beat on high speed until thick, about 5 minutes. Reduce speed to low. Beat in remaining lime curd. Raise speed to high, and beat 3 minutes. Pour over lime curd in crust, spreading evenly with an offset spatula; gently shake to remove any air bubbles. Refrigerate, uncovered, overnight. Garnish with zest before serving.