Set oven to 410F / 210C.
In a bowl, mix together the ingredients for the creamy spinach. Season to taste with sea salt & pepper. Pro-Tip: if you want to make the spinach creamier, then allow the spinach to thaw at room temperature, then place it in a paper towel and squeeze out the excess water.
Pat dry the chicken breast using a paper towel. Then, carefully slice the chicken breast down it’s side to create a deep pocket. Be careful not to completely remove the top.
Stuff the chicken with a few tablespoons of the creamy spinach, about two (2). Add a pinch of sea salt & pepper to the top of the stuffed chicken breast, then place it on a baking sheet lined with parchment paper. Lightly spray the top of the chicken breast
Bake in the oven for 22 to 25 minutes. To help brown the top of the chicken, set the oven to broil for the last 1 to 2 minutes.