Hi Lynn - it sounds like you enjoyed Queso Fundido, which means melted cheese. The most basic recipe would be only cheese and peppers (I believe that poblano peppers are used very often, but jalepenos would also be good, especially if you like things spicier).

Here is a more involved recipe I've made several times with rave reviews, and is one of my boyfriend's favorites. You can certainly simplify this and leave out any ingredient that doesn't suit your taste. I have added sauteed mushrooms to this with great success, as well.

Queso Fundido

2 roasted poblano chiles, peeled, seeded and finely diced (can be replaced with other peppers or canned mild chopped chiles, but try it with the poblanos - they are terrific!)
6 springs cilantro, finely chopped
1/2 cup finely diced chorizo (spicy smoked sausage - substitute with smoked Keilbasa or beef sausage if you can't find chorizo)
1/2 cup finely diced plum tomatoes, seeds removed
1 cup shredded white Cheddar cheese
1 cup shredded Monterey Jack cheese
1/2 cup grated mozzarella cheese
3 tablespoons grated Parmesan cheese
Warm tortillas, tortilla chips or cut-up raw vegetables, for serving

In a large bowl, toss together the chiles, cilantro, chorizo, tomatoes, and cheese. Mix
well and pour into an ovenproof, earthenware dish.

Place in a hot oven (400F). When the cheese begins to bubble (which may take up to 8 more minutes), remove the dish from the oven.

Serve immediately with the chips or vegetables.

Note - this works best in small batches instead of buffet-sized dishes, because the cheese mixture gets to hard to scoop when it cools off.