Preheat and Prep: Preheat your oven to 400°F (200°C). Generously grease a 9x13-inch baking dish or a large cast-iron skillet with butter or cooking spray.

Mix the Batter: In a large mixing bowl, combine the 4 boxes of Jiffy mix, 1 ⅓ cups of buttermilk, a splash of jalapeño juice, and 4 eggs. Stir until just combined.

Fold in the Peppers: Gently fold in the finely diced jalapeños so they are evenly distributed throughout the lumpy batter.

Rest the Batter: Let the batter rest for 3 to 5 minutes. The combination of buttermilk and the splash of jalapeño juice creates an acidic environment that activates the leavening agents, making the heavy batter rise beautifully.

Bake: Pour the batter into your prepared dish. Bake for 25 to 35 minutes. Because of the extra moisture from the jalapeños and juice, keep an eye on it around the 25-minute mark and bake until the top is golden brown and a toothpick comes out clean. The Sugar Topping: Pour the batter into your prepared dish and smooth the top. Sprinkle the turbinado sugar evenly across the entire surface of the batter right before putting it in the oven.

Cool and Serve: Allow it to cool for 10 minutes before slicing.