½ cup full-fat soy milk
¼ cup soy milk powder
1 tbsp arrowroot
½ cup brown rice syrup
1 tsp vanilla extract
1. In a small saucepan, whisk together soy milk, soy milk powder, and arrowroot. Stir constantly over medium heat until arrowroot is cooked and mixture starts to thicken, about 4 minutes. Stir in brown rice syrup, turn up heat to medium high, and bring to a gentle boil, then bring heat back down so mixture is at a low simmer, all the while stirring constantly. Cook until mixture is thick and slightly reduced, about 10 minutes. Sauce will have a thick consistency, like cake batter. Whisk in vanilla and remove from heat.
2. Allow to cool 10 minutes before spreading on warm cupcakes.
Tip: To measure out brown rice syrup, first rub canola oil on measuring cups. This will allow the syrup to slide easily out.