In a medium saucepan over medium heat, combine the Velveeta cheese, diced tomatoes with green chilies, cream cheese, and ranch dressing mix. Stir occasionally until the cheeses are melted and the mixture is smooth.

Gradually add the milk, stirring until you reach your desired consistency. If the queso is too thick, add more milk a little at a time.

Once the mixture is smooth, stir in the shredded cheddar cheese until melted and well combined.

Remove from heat and let it cool slightly before serving. If desired, garnish with chopped fresh cilantro.

Serve warm with tortilla chips for dipping.