Line an 8-inch square baking pan with parchment paper leaving some overhang for easy removal. Grease the parchment with one teaspoon butter. Set aside.
Combine the sugar, half and half, corn syrup, cinnamon, espresso powder, salt and chocolate in a 4 quart heavy saucepan with a wooden spoon. Bring to a boil, uncovered, without stirring over medium heat. Once mixture begins to boil, attach candy thermometer and cook to 235 degrees F (soft ball stage), without stirring, about 10-15 minutes.
Once the mixture reaches 235 degrees F, remove from heat, leaving thermometer attached. Add 2 tablespoons butter and vanilla and stir gently with wooden spoon. Allow the mixture to sit at room temperature until thermometer registers 120 degrees F.
Remove the thermometer and spoon mixture into a clean bowl. Stir vigorously with wooden spoon until mixture thickens and goes from shiny to opaque, about 15 minutes. If using a stand mixer, spoon mixture into mixer bowl and mix on medium high for about 10 minutes. Mix in coarsely chopped toffee, leaving just a bit for sprinkling on top.
Spoon the fudge into the prepared pan and spread evenly with a rubber spatula. Allow to sit at room temperature for at least 3 hours before cutting into 1-inch pieces.
Fudge can be stored in an airtight container for up to one week. I layer my pieces between sheets of parchment paper.