Place your mixing bowl and whisk attachment (or beaters) in the fridge or freezer for 10–15 minutes so they are well chilled before whipping the cream.
In the chilled bowl, add the softened cream cheese. Beat on medium speed for 1–2 minutes until completely smooth and creamy, scraping down the sides as needed so there are no lumps.
4 ounces cream cheese
Pour in the cold heavy whipping cream, powdered sugar, vanilla extract, almond extract (if using), and a pinch of fine sea salt. Start beating on low to avoid splattering, then increase to medium-high speed.
3 cups heavy whipping cream, 1 cup powdered sugar, 1 teaspoon pure vanilla extract, 1 teaspoon almond extract, fine sea salt
Beat the mixture for 2–4 minutes, watching closely, until stiff peaks form. When you lift the whisk, the cream should stand up and hold its shape without drooping.
Lightly spray a 9×13-inch baking dish (or an 8×8 or 9×9 pan for a taller cake) with nonstick spray or line the bottom with parchment paper for easier slicing.
1 tablespoon nonstick spray
Arrange a single layer of graham crackers (or chocolate wafers) in the bottom of the pan. Break pieces as needed to cover the surface; small gaps are fine.
2 sleeves graham crackers
Spread about 1½ to 2 cups of the whipped cream evenly over the cracker layer, pushing the cream all the way to the edges with an offset spatula or the back of a spoon.
Scatter a handful of mini chocolate chips or finely chopped dark chocolate evenly over the cream layer.
1 cup mini chocolate chips
Continue layering: crackers, whipped cream, then chocolate, until you run out of crackers, finishing with a thick layer of whipped cream on top. You will usually get 3–4 layers of cookies.
2 sleeves graham crackers, 1 cup mini chocolate chips
Smooth the final cream layer, then garnish with chocolate shavings, extra mini chocolate chips, or a light dusting of cocoa powder. If using fresh berries, add them shortly before serving rather than now.
1 cup mini chocolate chips, 1/2 cup chocolate shavings or curls, 1 cup fresh berries, 2 tablespoons unsweetened cocoa powder
Cover the pan tightly with plastic wrap or foil and refrigerate for at least 4 hours, preferably 8 hours or overnight, until the crackers have softened into cake-like layers.
When ready to serve, cut the icebox cake into squares with a sharp knife. For the cleanest slices, wipe the blade with a warm, damp cloth between cuts. Serve chilled.