Cut the chicken breast in half lengthwise so you have 4 thin chicken breasts. Season the chicken with salt and pepper.
Heat the olive oil in a large skillet or dutch oven over medium high heat. Add the chicken breasts and cook until golden brown on each side and cooked through to 165 degrees Fahrenheit in the middle (5 to 7 minutes each side).
Once the chicken is cooked through, remove it to a clean plate and cover to keep warm.
Add the butter and minced garlic to the skillet and continue to sauté over medium for one minute or just until the garlic begins to soften.
Add the chicken broth to the skillet and stir to dissolve the browned bits from the bottom of the skillet.
Cut the cream cheese into chunks and add it to the skillet along with the sour cream and mayonnaise.
Whisk the ingredients together and continue to cook over medium, whisking continuously, until the cream cheese is fully melted and the sauce is smooth. Add the milk and stir until smooth again.
Add the Parmesan and mozzarella cheese to the skillet. Continue to heat and whisk for a couple more minutes until the cheese is melted. Then stir the spinach into the sauce, a handful or two at a time, until wilted (this should only take about a minute), then stir in the artichoke hearts.
Return the chicken to the skillet and spoon the creamy spinach artichoke sauce over top. Cook for 2 to 3 minutes to warm the chicken back up. Serve hot.
