In a large bowl, whisk the eggs to combine, then whisk in the mustard. Whisk in one-quarter of the flour, followed by one-quarter of the milk. Continue to add the remaining flour and milk alternately until incorporated. Whisk in the salt and herbs. Let the batter rest at room temperature for about 1 hour.

Bring a pasta pentola filled with lightly salted water to a boil. Set up a large bowl of ice water (big enough to submerge the pentola insert). When you are ready to cook the spaetzle, pour about one-third of the batter into a spaetzle maker or large-holed colander. Hold the spaetzle maker or colander over the water and push the batter through the holes. Adjust the heat so that the water is at a simmer.

Once the spaetzle floats to the top, simmer them for another 30 seconds. Lift up the insert, draining the spaetzle well, and submerge the insert in the ice bath to chill. Drain the spaetzle and spread out on paper towels to dry. Return the insert to the pot and repeat with the remaining batches of batter. Place the spaetzle in a storage container and toss with a little canola oil to prevent sticking. Cover and refrigerate for up to a day.

To serve: Heat a film of oil in a large Copper-Core sauté pan over low heat. Increase the heat to medium, add the spaetzle, and sauté for about 5 minutes, tossing often, until the spaetzle are golden brown. Add the butter and toss to coat. Serve immediately topped with additional fresh herbs if desired.

Makes 6 cups