1. In a small bowl, whisk together the lemon juice, shallot, and 1 teaspoon of salt. Set aside to let the flavors meld.
2. In a large bowl, whisk together the eggs, egg white, garlic, spinach, milk, and heavy cream until well combined. Add the fresh herbs, flour, cornstarch, remaining teaspoon of salt, and black pepper. Whisk until the batter is smooth and no lumps remain.
3. Preheat your oven to 425°F (220°C). Place a 10-inch cast-iron skillet or oven-safe skillet in the oven to heat for about 10 minutes.
4. Carefully remove the hot skillet from the oven and add the butter, swirling it around to coat the bottom and sides of the skillet. Pour the batter into the skillet and immediately return it to the oven.
5. Bake for 20-25 minutes, or until the Dutch baby is puffed and golden brown. Remove from the oven and let it cool for a few minutes.
6. To serve, top the Dutch baby with smoked salmon and drizzle with the lemon shallot dressing. Garnish with additional fresh herbs and lemon slices, if desired. Enjoy!
Note: This Dutch baby is best enjoyed immediately, as it will deflate as it cools.
