How to Make It
Preheat oven to 425°F. Cook bacon in a 10-inch cast-iron skillet over medium, turning occasionally, until bacon is crisp and fat has rendered, about 10 minutes. Remove from heat; transfer bacon to a plate lined with paper towels. Reserve 1 1/2 tablespoons drippings in skillet.
While bacon cooks, process eggs, milk, flour, melted butter, salt, and pepper in a blender on medium speed until completely smooth, about 30 seconds, stopping to scrape down sides as needed.
Return skillet to medium heat; let heat 1 minute. Remove skillet from heat, and pour batter into skillet. Immediately transfer skillet to preheated oven. Bake until Dutch baby is puffed and golden brown, about 18 minutes. Do not open oven while cooking.
Remove Dutch baby from oven; immediately sprinkle with cheese. Return to oven; bake at 425°F until cheese melts, 1 to 2 minutes. Sprinkle with bacon and chives; serve immediately.