Preheat oven to 350° degrees F. Line a rimmed 15x10 jelly roll pan with foil and spray the foil liberally with cooking spray. Arrange the graham crackers in an even layer in the foil pan, breaking some crackers to fit if needed. Set aside.
In a medium saucepan, melt together the butter and brown sugar. Bring to a boil over medium heat and boil, stirring constantly for 2 minutes. Stir in the vanilla extract. Pour the toffee mixture evenly over the graham cracker layer, trying your best to cover all of the graham crackers. If you can't, no worries - once it bakes it will spread the toffee some more.
Bake for 10 minutes, then remove from the oven but keep oven on. Sprinkle the bag of chocolate chips over the surface of the toffee, then carefully return to the oven and bake for another 90 seconds. Remove from the oven and use an offset spatula or knife to spread the now melted chocolate chips into a smooth, even layer. Liberally sprinkle with the almonds.
Allow the toffee to set and cool and the chocolate to harden, about 30-40 minutes, before breaking into pieces. This can be expedited in the fridge, but I found that the chocolate tends to separate from the toffee layer more if refrigerated.