For the Squacho Cheese Sauce, melt butter in a sauté pan over medium-high heat. Add the white parts of the scallions and the garlic, and sauté until fragrant, about 1 minute. Add the flour and stir for a minute or two. Using a whisk, slowly mix the milk into the flour mixture until combined. Transfer to a blender and add cheese, butternut squash and pickled jalapeños and juice. Blend until smooth. Season with salt, pepper, cumin, smoked paprika and chili powder and blend again to combine. Pour back into the pan and keep warm over a low heat.
Preheat oven to broil.