1. Line an 8×8-inch baking pan with parchment paper and grease the sides.

2. In a medium saucepan, melt the butter over medium heat. Add the sugar, espresso powder, and salt, and stir constantly until the mixture comes to a boil.

3. Continue cooking, stirring frequently, until the mixture reaches 300°F on a candy thermometer, about 10-12 minutes.

4. Remove the pan from the heat and immediately pour the hot toffee into the prepared baking pan, spreading it evenly.

5. Sprinkle the chocolate chips over the hot toffee and let sit for 2-3 minutes until the chips have softened. Use a spatula to spread the melted chocolate evenly over the toffee.

6. Sprinkle the chopped pecans over the chocolate and gently press them into the surface.

7. Allow the toffee to cool completely at room temperature, about 2 hours.

8. Once cooled, lift the toffee out of the pan using the parchment paper and cut into squares or bars.