This icebox cake has the spirit of a Key lime pie and can be layered up in 10 minutes (if you’re not too precious about lining things neatly), then sent to the refrigerator to meld into a glorious tart-sweet-creamy-cakey pudding. But it has a salty secret: its structure comes from Ritz crackers. 

Ingredients

• 2 (14-ounce/396ml) cans sweetened condensed milk
• 2 cups (470g) heavy cream
• 1 Tablespoon  finely grated lime zest, plus more for serving
• 1/2 cup (120g) freshly squeezed lime juice (from about 8 limes)
• 10 ounces (285g) Ritz crackers (85 crackers, from about 3 sleeves)

Procedure

1. Whisk together the condensed milk and heavy cream in a large bowl until combined.
2. Add the lime zest and juice and whisk until thickened, about 1 minute.
3. Spread 1 cup (240ml) of the condensed milk mixture on the bottom of a deep-dish pie plate, an 11-inch (28cm) oval casserole, or a similar large shallow dish.
4. Top with a single layer of Ritz crackers.
5. Repeat, alternating layers of filling and crackers, until the dish is full, finishing with a layer of filling.
6. Cover and refrigerate for at least 2 hours or overnight—the longer you wait, the more the crackers will soften and meld with the filling.
7. Serve cold, zesting more fresh lime over the top, if you like.