Instructions:
- Preheat the oven to 375°F (190°C). Melt 1 tablespoon of butter in a 9 or 10-inch oven-safe cast iron skillet over medium heat on the stovetop, swirling to coat the sides.
- In a large bowl, whisk together the eggs, milk/cream, flour, salt, and pepper until just combined and slightly frothy. Avoid over-whisking, but ensure no lumps of flour remain.
- Gently fold in the grated Gruyère cheese, chopped chives, and parsley.
- Pour the egg mixture into the prepared, hot skillet. Let it cook undisturbed on the stovetop over medium-low heat for about 3–4 minutes, until the edges are just beginning to set, but the centre is still completely liquid.
- Dot the top surface with the remaining 1 tablespoon of cold butter, cut into small pieces. Immediately transfer the skillet to the preheated oven.
- Bake for 25–30 minutes. Do not open the oven door for the first 20 minutes. The omelette is done when it is deeply golden brown, puffed high, and the centre is no longer jiggly.
- Carefully remove from the oven. Let the Baked Omelette rest for 5 minutes before slicing and serving immediately.