Combine all ingredients in a mixing bowl and stir until smooth. Transfer a few tablespoons at a time to a colander with large holes set over a large pot of boiling water and press the batter through the holes. Stir gently to prevent the spaetzle from sticking together and boil until tender, 6 to 8 minutes. Drain thoroughly. Serve immediately, or reheat in a warm skillet immediately prior to serving.