• In a skillet with a lid, cook the chopped bacon until crispy, transfer to a paper towel to drain. Remove most of the bacon fat and add the arugula and a pinch of salt to the pan and cook over medium heat just to wilt the arugula. Remove to cool completely. Squeeze as much excess water as you can and then finely chop the arugula.
• Pre-heat oven to 400℉ generously butter each ramekin, coat the inside of the ramekin with some of the grated parmesan cheese, set inside the deep baking dish and set aside. Parchment paper the baking sheet lightly grease the paper and set aside.
• in a small saucepan over low heat, add the milk and ¼ teaspoon salt until warm and set aside.
• in a medium saucepan, melt the butter over low heat. Add the flour and cook for about 2 minutes whisking constantly until smooth. Gradually add the warm milk, whisking to remove any lumps 1-2 minutes. Remove from the heat and add most of the parmesan cheese, saving some to top each souffle. Add half of the Gruyere cheese. Briskly stir in the egg yolks and then the remaining Gruyere, cayenne pepper, chives, chopped arugula and bacon.
• In a separate bowl, whip the egg whites until stiff. Fold a quarter of the egg whites into the souffle base, then fold the remaining egg whites until just a few streaks of white are visible. Do not overmix. Divide mixture into each prepared ramekin and top with remaining grated parmesan cheese.
• Add hot water to the deep baking dish to reach halfway up the sides of the ramekin. Bake the souffles for 20-25 minutes or until they feel slightly set, a little jiggly. Remove ramekins from the water bath to cool on a wire rack. (The centers will fall a bit) Once cool enough to handle. Run a knife around the edges to loosen, tip each souffle into your hand, place them on the prepared baking sheet, right side up.
• Increase oven temp to 425℉. Return souffles to the oven for 10 minutes, until the puff up a little and brown. Sprinkle with pepper and serve.

Note

• You can do the initial bake, wait an hour while they cool and then do the final bake just before serving. You can also use a different cheese a Sharp Cheddar or Swiss type.