Preheat your oven to 375 degrees f.
Heat 1 Tablespoon of your oil in an oven-safe skillet over medium heat.
Add the shallots and cook until softened, about 2 minutes.
Add the spinach and cook until just wilted. Remove from the heat and let cool slightly.
In a bowl, combine the garlic powder, cottage cheese, egg whites, and wilted spinach plus shallots mixture. Stir well. Season with sea salt and pepper as desired.
Cut a pocket in each chicken breast by slicing horizontally (as shown), being careful not to cut all the way through.
Stuff each pocket with your spinach and cottage cheese mixture. Secure with toothpicks if needed.
Using the same skillet, heat the remaining Tablespoon of oil over medium-high heat.
Add the stuffed chicken to your hot skillet and cook for 3-4 minutes, just until seared. Carefully flip and cook for 2 minutes more on the other side until nicely golden brown.
Arrange your bell peppers and tomatoes around the chicken in the skillet.
Place the oven-safe skillet into your preheated oven for 25 to 30 minutes, or until the chicken is cooked through to 165 degrees in the thickest part using a meat thermometer.
Sprinkle with freshly chopped parsley if desired.
Enjoy while hot.