You’ll need a candy thermometer. Line a 9x13-inch pan with plastic wrap (a light spritz of non-stick spray on the pan first helps “glue” the plastic in place). In a heavy-bottomed pot, combine milk, corn syrup, sugar and chocolate. Cook over medium heat, stirring until sugar is dissolved. Once the sugar is dissolved, do not stir. Using a small pastry brush dipped in water, “wash” the sugar crystals off the side of the pot into the mixture, so it doesn’t start to crystalize and ruin your fudge. Once it’s all cleaned, leave it be and allow it to boil over medium-high heat. Cook to 238°F-240°F and remove from heat. Without stirring, add butter and allow to cool undisturbed until the mixture reaches 120°F. Add peppers and vanilla and beat with a wooden spoon by hand (or with a paddle attachment on an electric mixer) until the fudge starts to lose its glossiness and begins to thicken. Pour immediately into prepared pan and cut into squares when completely cool.