Mushroom and Spinach Omelet

Omelette with vegetable filling will make a light and satisfying dinner in combination with a simple side dish. While the cooked spinach mixture is infused, a little more liquid may be released from it; strain it so that the omelet does not become watery.
Preheat a medium-sized nonstick skillet over medium-high heat. Pour the oil into the pan; stir to coat. Add the shallots, garlic, mushrooms, and thyme; simmer for 7 minutes or until the mushrooms are lightly browned. Add the spinach; simmer for 4 minutes or until the liquid has almost evaporated. Remove the mixture from the pan; discard the thyme sprig. Wipe the pan thoroughly.Combine 1/4 teaspoon salt, 1/8 teaspoon pepper, and 4 eggs in a small bowl, stirring with a whisk. Return the skillet to medium-high heat. Add 1 1/2 teaspoons butter; whisk to coat. Add egg mixture; cook for 1 minute. Lift the edges of the omelet with a rubber spatula, tilting the pan to roll out the raw egg along the bottom of the pan. Cook for 1 minute or until the middle is just beginning to set, but still very soft. Place half of the mushroom mixture in the middle of the omelet; sprinkle with 1/4 teaspoon salt and 1/8 teaspoon pepper. Run a spatula around the edges and under the omelet to remove from the pan; fold in half. Place the omelet in a pile on a plate. Repeat the procedure with the remaining ingredients. Cut the omelet in half.