While traveling in Spain I was pleased to discover a long list of huevos, or egg, dishes on restaurant and hotel menus. Spanish cooks have created an impressive collection of egg specialties noted for their versatility and appeal.

Eggs are vital to the varied Spanish cuisine. They are not simply fried or boiled and served alone but are cooked in interesting fashion and combined with a wide variety of inviting foods.

Spain's national egg dish is the tortilla, or omelet, "round and yellow as a bullring," filled with tasty ingredients, and served flat rather than folded over. The popular "little cake" is fried in a small skillet until golden and crisp on both sides and is eaten hot or cold. It is not only served regularly in the home but is a common street snack and is carried as a luncheon staple by workers.

The most popular omelet, often called tortilla espanola is made by frying diced raw potatoes and onions in olive oil and adding beaten eggs and sometimes bits of chorizo (sausage) or ham.

A most attractive way to serve the omelets is a presentation called pastel de tortillas especial (special omelet cake). This dish is composed of four different small omelets of two eggs each (perhaps one potato, one shrimp, one mushroom and one mixed vegetable) piled atop each other with tomato sauce between each layer and on top. It is cut like a cake.

Here are recipes for three of the most appealing Spanish egg dishes.

SACRO MONTE OMELET (4serving) 1/2 pound chicken livers, cut up 3 tablespoons olive or vegetable oil 1 medium onion, peeled and mineed 1/2 cup diced cooked ham 2 large tomatoes, peeled and chopped 1 1/2 cups diced, cooked potatoes Salt, pepper to tast 6 eggs, lightly beaten

Saute onion and ham in oil in a medium skillet until onion is tender. Add chicken livers and cook until done, about 4 minutes. Add tomaties and cook 1 or 2 minutes. Add patatoes and season with salt and pepper. pour eggs over chicken liver mixture and tilt to spread evenly. Cook over low heat, and while cooking, lift edges of omelet with a knife to let wet egg mixture run underneath. When dry on top and golden on bottom, remove from heat. Invert on a plate placed over the top. Turn over. Grease skillet with oil, if necessary, and return omelet to the pan. Cook until golden on other side. Serve at once cut into wedges.

COSTA BRAVA BAKED EGGS WITH SEAFOOD (4 servings) 1 large onion, peeled and sliced or chopped 1 or 2 garlic cloves, crushed 2 tablespoon olive or vegetable oil 1 1/2 cups tomato sauce 1 medium green pepper, cleaned and chopped 1/2 tespoon dried thyme Salt, pepper to taste 2 cups small cooked shrimp 1 cup diced, cooked scallops or other fish 8 eggs 1/2 cup dried breadcrumbs (about) 1/4 cup grated Parmesan cheese 4 flat anchovy fillets, drained and cut in halves (optional)

Saute onion and garlic in oil in a medium skillet until tender. Add tomato sauce, green peper, thyme, salt and pepper. Cook slowly, uncovered, 10 minutes. Add clams, shrimp and scallops and cook 1 minute. Spoon into a large shallow baking dish. Carefully break the eggs over seafood mixture. Sprinkle with breadcrumbs and cheese. Arrange a half anchovy fillet over each egg, if desired. Bake in a precheated 375-degree oven until eggs are set, about 10 minutes. Serve at once.

SPANISH EGGS, FLAMENCO STYLE (4 servings) 1 large onion, peeled and chopped 1 or 2 garlic cloves, crushed or mineed 2 tablespoons olive or vegetable oil 1 cup diced chorizo (Spanish sausage) or ham 2 tomatoes, peeled and chopped 2 tablespoons chopped, fresh parlsey Salt, pepper to taste 1/2 cup chicken broth 8 eggs 1 cup cooked green peas 16 cooked or canned asparagus tips 2 canned pimientos, drained and cut into silvers 4 cooked artichoke hearts Saute onion and garlic in oil in a skillet until tender. Add chorizo or ham and cook 1 minute. Mix in tomatoes, parsley, salt and pepper. Pour in chicken broth and cook slowly, uncovered, about 5 minutes. Spoon mixture into 4 individual shallow baking dishes. Carefully break 2 eggs over the ingredients in each dish. Arrange peas, asparagus and pimientos around eggs. Place an artichoke in center of each dish between the eggs. Bake in a preheated 375-degrees oven until eggs are just set, about 10 minutes. The whites should be set but the yolks a little runny. Serve at once.