Pulse graham crackers in a food processor until finely ground, about 10 to 15 times. Add melted butter and ½ teaspoon salt; pulse until crumbs are evenly moistened. Transfer the crumb mixture to a springform pan, and press onto bottom and about 1 ¼ to 1 ½ inches up sides. Freeze for 30 minutes.

In a clean food processor, combine sliced peeled peaches, 6 tablespoons agave, and ½ teaspoon salt; process until smooth, about 2 minutes. Transfer to a large bowl, and refrigerate until chilled, about 30 minutes.

In a clean food processor, combine cream cheese, ricotta, powdered sugar, lemon juice, remaining 4 tablespoons agave, and remaining ½ teaspoon salt. Process until very smooth, about 2 minutes. Transfer to a second large bowl.

Spread half of cream cheese filling in prepared crust in an even layer; freeze for 45 minutes. Chill the remaining cream cheese filling. Spread half of chilled peach puree in an even layer on top of cream cheese filling in pan; freeze for 45 minutes. Spread remaining cream cheese filling in an even layer on top of the peach layer; freeze for 45 minutes. Spread remaining peach puree on top. Cover pan with plastic wrap; freeze until firm but not completely frozen, 3 to 4 hours.

Alternatively, freeze overnight and let thaw for 45 minutes before serving.

Remove sides of pan; transfer cheesecake to a serving plate. Top with unpeeled peach slices.