How to Make It
In a small saucepan, combine the heavy cream and milk and bring just to a simmer. Transfer to a large heatproof bowl set over a saucepan of simmering water. Add the three cheeses and heat, whisking occasionally, until completely melted, 7 to 10 minutes. Add the garlic powder and gradually whisk in the buttermilk; heat until thoroughly incorporated and the queso is very smooth, about 5 minutes. Keep warm over very low heat and serve with tortilla chips, cilantro and fresh salsa.