Crunchy peanut brittle bars made with piloncillo are a classic Mexican candy. This family-friendly snack offers a satisfying crunch with a traditional caramelized flavor.
Line a baking sheet with parchment paper and set aside for quick transfer once the candy is cooked.
Place a heavy-bottomed saucepan over medium heat and combine piloncillo (or packed dark brown sugar), water, lime juice, and salt. Stir gently until the piloncillo dissolves and the mixture comes to a boil.
Let the syrup simmer, without stirring, on medium-low heat for about 8-10 minutes. Use a candy thermometer if available; target 300°F (hard crack stage) for a glassy, crisp texture.
Immediately add the raw peanuts to the syrup, reduce heat to low, and stir constantly. Continue cooking for about 2-3 more minutes, making sure all peanuts are coated and the sugar just begins to caramelize with a deep amber color.
Quickly pour the mixture onto the prepared baking sheet. With a lightly greased spatula, spread and press to about 1/4 inch thickness. Work swiftly before the mixture hardens.
Let cool completely at room temperature (about 20 minutes), then break or cut into bars. Store airtight to maintain maximum crunch.