This cake cuts the fat you’d find in most traditional icebox cakes by replacing heavy cream with fat-free sour cream. Lime juice gives the recipe an extra kick of flavor!
Line a 9- x 5-inch loaf pan with 2 sheets of plastic wrap (one horizontal, and the other vertical). Let the edges overhang on each side by about 4 inches.
With a whisk, combine sour cream, 1 cup sugar, vanilla, and a dash of salt in a large bowl until blended.
Arrange a layer of about 14 overlapping chocolate wafers in 2 lines on the bottom of the loaf pan, keeping the layer as level as possible. Spread with 1 cup of the sour cream mixture; repeat in the same way with 2 more layers of wafers and cream, ending with cream layer. (You may have wafers left over.) Cover with plastic wrap, and refrigerate until wafers are very soft (at least 12 hours).
Meanwhile, pulse 2 packages of berries in a food processor just until broken up. Add remaining 1/3 cup sugar, water, lime juice, and remaining dash of salt; pulse once or twice. Pour mixture through a coarse strainer; set over a bowl, pressing hard on solids to extract as much liquid as possible (you should have 1 cup). Refrigerate, tightly covered, until thoroughly chilled (about 1 hour); stir before using.
Lift icebox cake out of pan using over-hanging plastic wrap; transfer to a large plate. (Be careful, cake will be very soft.)
Carefully flip cake onto a cutting board, so that the chocolate wafer layer faces up. Peel back plastic wrap. Using a sharp serrated knife, cut cake crosswise into 10 slices, wiping knife clean after each cut. Arrange each slice on a plate, and pour a small pool of raspberry sauce on each plate; garnish evenly with remaining package of raspberries. Serve immediately with remaining sauce.