Prepare the Cheese Mixture: In a medium saucepan, combine the cubed Velveeta cheese, shredded cheddar cheese, and heavy cream (or whole milk). Heat over medium heat, stirring constantly until the cheese melts and the mixture becomes smooth and creamy.
Add Spices and Salsa: Stir in the chili powder, cumin, garlic powder, paprika, and salt and pepper to taste. Add the salsa or diced tomatoes and mix well to incorporate the fresh flavor. If you prefer a spicier queso, add the diced jalapeños or a bit of hot sauce.
Simmer: Reduce the heat and let the queso simmer for a few minutes, stirring occasionally. If the queso is too thick, add more milk or cream to adjust the consistency to your liking.
Serve: Once the queso is smooth, creamy, and heated through, pour it into a serving dish. Serve immediately with tortilla chips, fresh veggies, or over nachos, tacos, or baked potatoes.