Melt butter in a large skillet over medium heat. Once melted, add in the shallot and cook until softened, about 3 minutes. Add garlic and jalapeño and cook until fragrant, about 1 minute more. \nWhisk in the half \u0026amp; half, Yucatán sauce and cornstarch until well combined. Allow the mixture to come to a gentle simmer. Reduce the heat to low and slowly add in the shredded cheese, a few handfuls at a time, making sure the cheese is melted before the next batch is added. \nOnce all the cheese is added, stir in the green chilis and ½ tsp salt. Transfer to a serving bowl and top with chopped cilantro and an additional drizzle of Yucatán sauce. Serve warm, alongside warm tortillas or tortilla chips.