1 c. semi-sweet chocolate chips
2 Tbsp. unsalted butter
1/8 c. milk (2% or whole milk is best here)
Combine all ingredients in a small saucepan over low heat. Stir every couple of minutes until the chocolate starts melting, once the chocolate is mostly melted remove from heat and stir sauce until smooth.
The sauce can be refrigerated if you have leftovers, and then reheated in the microwave for about 10 seconds to use again.