The fudge comes together in mere minutes in the microwave, creating dense, chocolatey fudge that lasts well at room temperature or in longer-term storage in the fridge. Adjust the amount of cayenne pepper to your preferred heat level!
Line an 8 or 9-inch square pan with aluminum foil or parchment paper. Lightly grease it.
Use a microwave or sauce pan to melt together the chocolate and sweetened condensed milk. If you're using the microwave, use short bursts of 20-30 seconds and stir well between each.
Once the chocolate mix is smooth, pour in the vanilla extract, cinnamon, and cayenne pepper. (Note that 1/8 teaspoon provides a little flavor, not much heat, so add cayenne and taste to adjust to desired heat level.)
Immediately pour the fudge into the prepared pan. Smooth out to edges and sprinkle salt all over the top. Let set in fridge at least four hours before cutting. Keeps in covered dish in fridge for upwards of a week.