In a skillet over medium heat, cook onions, garlic & olive oil for 3-4 minutes, until softened.
Add kale and red pepper flakes and cook another 2-3 minutes until kale is wilted.
Spray two oven safe ramekins with cooking spray and spoon 2 tablespoons of sauce into the bottom of each.
Next, add half the kale and onion mixture between the two ramekins then half the feta, the remaining 2 tablespoons of sauce, then the remainder of the kale.
Crack an egg into each ramekin and sprinkle remaining feta on top of that. Season with salt and pepper.
Bake for 12-15 minutes until eggs are fully cooked but still runny.
Serve warm with crusty bread.
Notes
For a heartier meat option - add ground sausage to the skillet with the onions, garlic and kale and cook until browned.