- Crack eggs into a medium-size bowl. Whisk eggs together with half-and-half and salt. Heat salsa in small bowl in the microwave so it is very warm.
- For each omelet, heat a small 6-inch nonstick skillet (or well-seasoned cast-iron skillet) over medium-high heat until pan is hot. Add ½ tablespoon of the oil, let heat a few seconds, then add ½ of the egg mixture. Reduce heat to medium. With a fork, stir eggs every few seconds to create large curds, then let cook until still creamy but set enough to hold together, about 30 seconds. Spoon ½ of the shredded cheese and watercress across the center of the set eggs. Immediately roll the omelet out onto a serving plate. Spoon salsa down the center of the omelet. Sprinkle with grated cheese and serve right away