In a medium pan over medium high heat, add 1 Tbsp Olive Oil.
Season chicken with salt and pepper. Once the pan is hot, add the chicken breasts to the pan and sear until done and no longer pink inside. Cooking time depends on the thickness of your chicken breasts. I generally use thin breasts and cook for about 5 minutes per side.
Once the chicken is cooked through, remove from the pan and set aside.
Lower pan to medium low and add the butter and onion and cook until translucent.
Next, add garlic and cook an additional 2-3 minutes until fragrant.
Add the feta and cream and mix until feta has melted.
Add the spinach and cook until wilted, about 3-5 minutes.
Slice the chicken breasts horizontally into pieces and place on a serving dish. Top the chicken with the feta cream mixture and serve.