Gently melt the butter in a medium pan over low heat until melted (using low heat takes a little longer, but we want to keep it creamy).
Remove the pan from the heat to prevent the sauce from breaking. Then, whisk in the garlic powder and hot sauce until a cohesive sauce forms, about 1 minute. Taste, then if you want the sauce more spicy, add a pinch or more cayenne pepper.
Use immediately or store in an airtight container or jar in the refrigerator for up to 2 weeks. It will harden, so reheat gently over low heat and whisk or shake if separated.
