01 - Combine sliced peaches with lemon juice and sugar in a large bowl. Toss gently to coat evenly. Let stand at room temperature for 10 minutes, allowing fruit to macerate and release natural juices.
02 - In a chilled mixing bowl, beat cold heavy cream using a hand mixer or stand mixer on medium-high speed until soft peaks form. Be careful not to overbeat.
03 - In a separate large bowl, combine softened mascarpone cheese, sugar, and vanilla extract. Beat with mixer on medium speed until completely smooth and creamy, approximately 2 minutes.
04 - Add one-third of the whipped cream to the mascarpone mixture and fold in gently using a rubber spatula. Repeat with remaining whipped cream in two additions, folding until just combined and no streaks remain.
05 - Whisk together peach juice and peach schnapps (if using) in a shallow dish wide enough to accommodate ladyfingers.
06 - Working quickly, dip each ladyfinger into the peach juice mixture for 1-2 seconds per side. Ladyfingers should be moistened but still firm—do not oversaturate.
07 - Arrange 12 soaked ladyfingers in a single tight layer at the bottom of a 9x7 inch serving dish. Spread half of mascarpone cream evenly over ladyfingers using an offset spatula. Layer half of macerated peach slices over cream.
08 - Repeat with remaining soaked ladyfingers, spreading with remaining mascarpone cream and topping with remaining peach slices. Smooth top surface with spatula.
09 - Cover dish tightly with plastic wrap and refrigerate for minimum 4 hours, preferably overnight. This allows flavors to meld and texture to set properly.
10 - Remove from refrigerator 15 minutes before serving. Garnish with fresh mint leaves. Serve chilled, scooping portions with a large spoon to maintain layered structure.