Ingredients

• 5 large fresh or 1 cup frozen, defrosted or canned, chopped hatch chiles, drained, squeezed dry
• 3 tablespoons unsalted butter
• 2 tablespoons grated onion
• 3 garlic cloves finely grated using a microplane
• 1/2 teaspoon kosher salt
• 2 tablespoons all-purpose flour
• 1/2 teaspoon ground cumin
• 1 1/2 to 2 cups whole milk
• 4 cups grated Cheddar cheese (nothing fancy!)
• 2 cups grated Monterey Jack cheese
• 2 plum tomatoes, seeded, diced, drained
• Roughly chopped cilantro (for serving)
• White-corn tortilla chips (for serving)

Instructions

1. If using fresh chiles, place on a foil-lined baking sheet and broil until blistered, 5 to 7 minutes per side. Place in a bowl, cover with plastic wrap, and let steam for 5 minutes. Remove skins, stems, and seeds. Chop chiles, drain on paper towels, and set aside.
2. In a medium pot over medium-low heat, melt the butter. Add the onion, garlic, and salt and cook, stirring, until lightly browned and liquid has evaporated, about 2 minutes more. Whisk the flour and cumin into the butter mixture and cook until lightly browned, 30 seconds to 1 minute.
3. Raise the heat to medium and slowly whisk in the milk. Whisk constantly until sauce is thick enough to coat the back of a spoon, about 5 minutes.
4. Lower the heat to medium-low and add the cheeses, 1/4 cup at a time. Stir until cheese has melted completely before adding more cheese.
5. Fold in the tomatoes and chiles. Taste and adjust seasoning. Sprinkle with cilantro and serve immediately with chips alongside.