Why This Recipe Works
For a frozen yogurt that’s dense and creamy—not icy and rock-hard like most versions—the key was controlling the water in the base so that the number of large ice crystals that formed during freezing was minimized. Since Greek yogurt is strained of excess liquid during processing, it seemed like a logical starting point, but it produced a chalky frozen yogurt. We got much creamier results when we used plain whole-milk yogurt that we strained of excess liquid ourselves. We also found that swapping in a few tablespoons of Lyle’s Golden Syrup for some of the granulated sugar played an important role. Unlike granulated sugar, which is made up of larger sucrose molecules, Lyle’s is about 50 percent invert sugar, which is made up of smaller glucose and fructose molecules. These smaller molecules are much better at depressing freezing point, so more of the water in our frozen yogurt base stayed in liquid form, delivering a frozen yogurt that not only contained fewer ice crystals but also was more scoopable straight from the freezer. The final step in managing the water was to trap some of it using unflavored gelatin. By dissolving and heating just 1 teaspoon of gelatin in a portion of the strained whey, we prevented even more water molecules from joining together and forming large ice crystals.