Line a rimmed baking sheet with parchment paper and set it aside.
In a heavy-bottomed saucepan, combine the unsalted butter, granulated sugar, light brown sugar, brewed coffee, corn syrup, and salt. Stir over medium heat until the butter melts and sugars dissolve.
Attach your candy thermometer to the saucepan. Increase heat to medium-high and stir continuously. Cook until the mixture reaches 300°F (hard crack stage), about 10-15 minutes.
Once the mixture reaches 300°F, remove from heat and stir in half of the toasted slivered almonds. Pour the hot toffee onto the prepared baking sheet, spreading it evenly.
While the toffee is still hot, sprinkle the dark chocolate chips evenly over the top. Let sit for a few minutes to allow the chocolate to melt, then spread it over the toffee.
Sprinkle the remaining toasted almonds over the melted chocolate, pressing them gently to ensure they stick.
Allow the toffee to cool completely at room temperature until it hardens, about 1-2 hours. Once cooled, break into pieces and enjoy!
