Spread almonds on a baking sheet and toast for about 6 minutes, until golden.
Line a 12 x 17" rimmed baking sheet with a silicone mat or lightly buttered parchment paper. Arange the saltine crackers on the baking sheet in a single layer, patching any holes with cracker bits; slight gaps are okay.
In a medium saucepan, combine the sugar, butter, and corn syrup and cook over low heat until the sugar is melted. Brush the side of the pan with a moistened pastry brush to wash down any sugar crystals. Cook the syrup over moderate heat without stirring until it starts to brown around the edge, about 5 minutes. Insert a candy thermometer into the syrup and simmer, stirring with a wooden spoon, until a honey-colored caramel forms and the temperature reaches 300 degrees, about 6 minutes longer.
Slowly and carefully pour the caramel over the crackers, being sure to cover most of them evenly. Using an offset spatula, spread the caramel to cover any gaps. Let cool for 3 minutes, then sprinkle the chopped chocolate evenly on top. Let stand until the chocolate is melted, about 3 minutes, then spread the chocolate evenly over the toffee. Spread the almonds evenly over the chocolate. Freeze the toffee until set, about 15 minutes.
Invert the toffee onto a work surface and peel off the mat or paper Invert again, break into large shards and serve.
The chocolate-almond saltine toffee can be refrigerated for up to 2 weeks in an airtight container.