1. Prepare the Chicken Marinara Base: Heat olive oil in a large skillet or pot over medium heat. Add the chopped onion and cook until softened, about 5 minutes. Stir in the minced garlic and cook for another minute until fragrant, being careful not to burn it.

2. Add Tomatoes and Seasonings: Pour in the crushed tomatoes and chicken broth. Stir in the dried oregano, dried basil, and red pepper flakes (if using). Season with salt and black pepper to taste. Bring the sauce to a gentle simmer.

3. Cook the Chicken: While the sauce is simmering, cut the chicken breasts into 1-inch cubes. Add the chicken pieces directly to the simmering marinara sauce. Ensure the chicken is fully submerged.

4. Simmer and Thicken: Reduce the heat to low, cover the skillet, and let the chicken marinara simmer for 15-20 minutes, or until the chicken is cooked through and tender, and the sauce has slightly thickened. Stir occasionally to prevent sticking. The chicken should be opaque throughout.

5. Make the Peanut Butter Protein Shake: While the chicken marinara simmers, combine the almond milk, vanilla protein powder, natural peanut butter, optional banana, and ice cubes in a blender.

6. Blend the Shake: Blend on high speed until completely smooth and creamy. If it’s too thick, add a splash more almond milk; if too thin, add a few more ice cubes.

7. Serve the Marinara: Once the chicken is cooked, remove the skillet from the heat. Garnish the chicken marinara with fresh chopped parsley before serving.

8. Enjoy: Serve the chicken marinara warm, perhaps alongside a simple green salad or steamed vegetables. Enjoy the peanut butter protein shake immediately.