Preheat oven to 400 degrees Fahrenheit. Line a baking sheet with aluminum foil, grease it, and set aside.

Line another baking sheet with aluminum foil and arrange the slices of bacon evenly on it.

Bake for 20 minutes, or until nice and crispy.

Place bacon on a paper towel-lined plate to drain.

Measure out bacon fat and add to it enough butter to equal 8 ounces all together (in my case, I had 3 1/2 ounces bacon fat, so I only needed 4 1/2 ounces of butter).

Crumble up bacon and set aside. (I used my kitchen shears to cut it up finely.)

In a large, heavy-bottomed pan, combine the bacon fat, butter, sugar, and warm water. Attach a calibrated candy thermometer and cook over medium heat until it reaches hard crack stage (about 30 minutes), stirring constantly with a silicone spatula. You can use a silicone brush dipped in water to try to wash down sugar crystals from the sides of the pan in the first few minutes of cooking, but try not to scrape too much after that to prevent crystallization.

Once the mixture has reached hard crack stage, remove from heat immediately.

Remove the candy thermometer and add to the mixture about half the bacon crumbles and the Frangelico. It will bubble up once the Frangelico is added--be careful!

Stir until the foaming mostly stops, then spread in the prepared baking sheet.

Sprinkle the chocolate chips over the top and let sit for a few minutes.

Spread the melted chocolate chips over the top of the toffee and sprinkle over it the remaining bacon crumbles.

Let sit until chocolate is set, then break into pieces. (I was impatient and popped the sheet into the fridge to set.)

Store in an airtight container in the refrigerator for up to one week.