Preheat oven to 350 degrees. Line the bottom and sides of an 8-inch square baking pan with foil; coat with nonstick cooking spray.
In a medium bowl, combine graham cracker crumbs, sweetened condensed milk, and salt; stir until moistened. Stir in 1 1/2 cups sliced almonds.
Spread mixture evenly in prepared pan (if mixture is very sticky, pat in with moistened fingers). Sprinkle with remaining 1/2 cup sliced almonds, patting in gently.
Bake until golden and a toothpick inserted in the center comes out clean, 35 to 40 minutes. Cool completely in pan.
Remove from pan; peel off foil, and cut into 16 squares with a serrated knife.
Squares will keep, in an airtight container at room temperature, for 4 to 5 days.