Preheat the oven to 350°F Line a 13- by 9-inch cake pan with foil, then coat with cooking spray.
In a large bowl, combine the butter and graham cracker crumbs, then press firmly into the bottom of the prepared pan. In the same bowl, stir the cinnamon, salt, and cayenne. Scatter the chocolate over the crust, then sprinkle with the cinnamon mixture. Scatter the coconut and peanuts on top, then pour the condensed milk over the whole mixture.
Bake until golden brown and set, about 40 minutes. Cool completely in the pan on a wire rack. Lift out with the foil, then cut into 3-inch squares.