Sauté the Vegetables:
Heat the butter in a medium saucepan over medium heat. Add the chopped onion and jalapeño. Sauté for about 5 minutes, or until the onion becomes translucent and soft. Stir occasionally to prevent burning.

Add Milk and Cream Cheese:
Pour in the whole milk, stirring to combine. Then, add the cream cheese and continue stirring until the cream cheese is fully melted into the milk.

Melt the Cheese:
Gradually add in the shredded cheddar cheese, stirring constantly until the cheese has melted and the mixture becomes smooth and creamy. If the queso is too thick, add a little more milk until you reach the desired consistency.

Spice It Up:
Stir in the garlic powder, cumin, salt, and pepper. Keep stirring until the spices have fully blended with the cheese mixture.

Add the Tomatoes:
Fold in the diced tomatoes with green chilies, and continue to stir for 1-2 minutes, allowing the flavors to combine.

Serve:
Once everything is melted and smooth, your queso is ready to serve. Transfer it to a serving dish and enjoy with your favorite chips, veggies, or grilled meats!