Line a baking sheet with parchment paper. Preheat a medium cast-iron skillet over medium heat. Add the almonds and toast, stirring often, for 3 to 5 minutes, until lightly browned. Sprinkle the brown sugar and salt over the almonds and cook, stirring almost continuously with a wooden spoon, until the brown sugar is completely melted and darkened in color, watching the skillet carefully so the almonds don't burn, 3 to 5 minutes. Spread the almonds in a single layer on the prepared baking sheet and let cool completely, then break up any clumps with your hands and get to work on eating your fill.
Make in small batches because of crack almonds' addictive nature.