01 - Beat the softened butter and brown sugar with a hand mixer or stand mixer on medium speed until light and fluffy, about 2 minutes.
02 - Pour in the milk and vanilla extract, then beat until fully incorporated and smooth.
03 - Gradually add the heat-treated flour and salt, mixing on low speed until just combined.
04 - Gently fold in the mini chocolate chips using a rubber spatula until evenly distributed.
05 - Use immediately to frost cooled cupcakes, cakes, or brownies, or refrigerate for up to 3 days. If chilled, bring to room temperature and stir before using.