Preheat your oven to 425ºF (220ºC) and place a 12-inch cast iron skillet inside to heat up.

In a large mixing bowl, whisk together 1 cup of all-purpose flour, ½ teaspoon of kosher salt, ¼ teaspoon of freshly ground black pepper, and ½ cup of the sharp cheddar cheese.

In another bowl, crack 8 large eggs, add ¾ cup of whole milk, ¼ cup of finely chopped chives, and ½ teaspoon of mustard powder, then whisk until smooth.

Gently pour the wet ingredients into the dry ingredients, stirring until just combined.

Carefully remove the hot skillet from the oven and add 2 tablespoons of unsalted butter, allowing it to melt.

Once the butter is melted, pour the prepared batter into the skillet, filling it no more than ¾ full.

Bake in the oven for 15 minutes, then sprinkle the remaining ¾ cup of cheddar cheese over the top.

Return to the oven and bake for an additional 10 minutes, until puffed and golden brown.

Slice your Dutch Babies using a spatula, serve warm, and garnish with optional toppings.