Melt 2 tablespoons butter in a saucepan over medium heat
Whisk in 2 tablespoons flour and cook for 1 minute
Slowly add 1 cup milk, whisking until smooth
Reduce heat to low
Add 2 cups shredded cheese, a little at a time, stirring until melted
Stir in 1 can diced tomatoes with green chiles, drained
Add 1/2 teaspoon salt
Add 1/4 teaspoon garlic powder
Add 1/4 teaspoon cumin
Stir until smooth and creamy
Serve warm with chips, tacos, or vegetables