Chile Con Queso

Bahan-bahan (2 porsi)

• 2 tablespoons unsalted butter
• 2 tablespoons all-purpose flour
• 2 cups half-and-half
• 2 cups (8 oz) Mexican blend shredded cheese from a bag (I use Tillamook; see note)
• ½ teaspoon salt
• ½ teaspoon chili powder
• ½ teaspoon cayenne pepper
• ¼ teaspoon ground cumin
• ¼ teaspoon garlic powder
• ¼ teaspoon onion powder
• 1 cup canned diced tomatoes and green chiles, (such as Rotel (from a 10-oz/283-g can))
• 1 tablespoon fresh chopped cilantro ((optional))
• Tortilla chips, (for serving)