Preheat the broiler to high and position a rack in the top third of the oven.

Add the bacon to a 12 inch nonstick oven proof skillet and place over medium heat. Cook, stirring often with a rubber spatula until the bacon is crispy and golden brown, about 10 minutes. Using a slotted spoon remove the bacon to a plate and remove all but 2 tablespoons of the bacon fat from the pan. Add the red onion to the pan along with the hash browns. Stir in 1/2 teaspoon salt and spread the mixture evenly over the bottom of the pan. Cook undisturbed for 3 minutes or until the potatoes are beginning to brown and get crispy. Using a rubber spatula, stir the potato mixture. Re-spread the mixture evenly on the bottom of the pan and cook undisturbed for another 2 minutes to brown a bit more. Add the kale and another 1/2 teaspoon salt and cook until the kale is wilted, another 2 minutes. Stir in the reserved bacon.

Meanwhile in a medium bowl whisk together the eggs, heavy cream and remaining 3/4 teaspoon salt. Add the grated cheddar and mozzarella cheese. Add the egg mixture to the pan and stir to combine. Cook, stirring occasionally with a rubber spatula until the mixture looks like loose scrambled eggs, about 2 minutes. Cook for 1 minute longer undisturbed to set the bottom. Place the pan under the broiler for about 3 to 4 minutes or until the top is golden brown and the eggs are set. Allow to cool for 5 minutes before slicing into wedges and serving.