01 - In a medium saucepan set over medium heat, combine the whole milk and softened cream cheese. Stir continuously with a whisk or wooden spoon until the cream cheese has fully melted and the mixture is smooth and uniform, approximately 2 to 3 minutes.
02 - Add the shredded cheddar and Monterey Jack cheese one handful at a time, stirring constantly after each addition. Continue stirring until all the cheese has melted completely and the dip reaches a silky, creamy consistency.
03 - Fold in the finely chopped jalapeño, diced tomato, chives or green onions, minced garlic, ground cumin, smoked paprika, and a generous pinch of salt and pepper. Stir until all seasonings and vegetables are evenly distributed throughout the dip.
04 - Continue cooking over medium-low heat for 3 to 5 minutes, stirring frequently to prevent scorching on the bottom, until the dip thickens slightly and coats the back of a spoon.
05 - Transfer the warm dip to a serving bowl. Present immediately alongside tortilla chips, crusty bread, pretzels, or an assortment of fresh vegetables such as celery sticks and bell pepper strips.