Fudge is one of the most finely crystalline candies, dissolving to a creamy consistency on the tongue. Sugar, milk, fat and chocolate solids have to be assembled in such a way that they are solid yet retain moisture and melt-in-your-mouth. Of course the magic ingredient is temperature!
Developing these textures and flavors requires the home cook to walk a fine line between super saturation and crystallization. That is, using temperature to control both the amount of moisture (saturation) in the fudge mixture and the texture (crystallization) of the fudge to ensure a smooth, creamy feel.
Achieving the right amount of moisture in the fudge requires heating the mixture to just the right temperature. Whereas developing the smooth and creamy textures characteristic of amazing fudge is all in how you allow the mixture to cool down.
Here’s how you do it:
Set aside 6oz of chocolate and butter cubes in the freezer. Cover a 13X9in baking dish with aluminum foil and coat with butter. Fill your sink 1-inch deep with water set to room temperature (67-77°F).
Combine chocolate, sugar, salt, chocolate syrup and milk in a heavy pot over medium heat – stir constantly. Scrape the sides of your pot with a pastry brush dipped in hot water to help dissolve formed sugar crystals and insure a smooth texture. Cook the mixture until it has reached 235-240°F – the “Soft ball” stage.
A Super-Fast® Thermapen® is the perfect tool for spot checking your fudge at this stage. The fast and accurate temperatures will let you know the moment your mixture has reached the desired temperature. Cook to higher temperatures at this point and you may be left with dry, brittle fudge.
Quickly transfer the pot to the water in the sink. Sprinkle frozen butter, the remaining chocolate and vanilla over the top of the mixture. Cool the pot in the sink for 5 minutes then transfer the pot to the counter and allow to cool undisturbed until the temperature has reached 110°F.
It’s important that you don’t disturb the mixture until it’s reached the desired temperature. Doing so will actually further the crystallization of the sugar into large granules upsetting the smooth and creamy texture. The smaller the crystals, the creamier and smoother the fudge will be.
A leave-in thermometer, like ChefAlarm is ideal for this step in the process. ChefAlarm’s Pro-Series probes can be attached to the side of the pot with an included pot clip and a low alarm set to alert you when the desired 110°F temp is reached. That leaves you to tackle other important tasks around the house.
Once at 110°F, incorporate the unmixed ingredients and continue stirring until the fudge loses its shine and becomes difficult to stir, about 8-12 minutes.
Transfer your fudge to a the prepared pan and spread with a spatula until even. Cool at room temperature (67-77°F) until firm; this should take about 4 hours. Remove from pan and cut into desired serving size.
6 tbsp unsalted butter, cut into 1/2 cubes
12oz unsweetened chocolate, roughly chopped
4 1/2 cup granulated sugar
1 1/2 cups light brown sugar
1 tsp salt
3 tbsp chocolate syrup
2 1/2 cups whole milk
1 tbsp vanilla extract
Harold McGee – On Food and Cooking: The Science and Lore of the Kitchen
America’s Test Kitchen – Old-Fashioned Chocolate Fudge
Foodsciencetv – Fudge Science