Preheat the oven to 425°F. Place an 8-inch cast iron skillet into the oven to preheat.
In a medium mixing bowl, whisk together the eggs, milk, sourdough discard and flour, until a smooth batter forms.Have the sliced ham, grated cheese and bacon ready. Once the skillet has preheated, add the butter and allow to bake until butter is melted, about 3 minutes.
Carefully remove the pan from the oven and pour the batter over the melted butter. Lay the ham over the batter, sprinkle with the cheese and bacon. Immediately return the pan to the oven. Bake until golden brown, dramatically risen, and puffy, about 30 minutes.
Serve immediately.