Preheat oven to 400°F. Prepare a baking dish with a spritz of nonstick cooking spray.
Pat the chicken dry with paper towels. Use a basting brush to spread the mayonnaise evenly over the tops of the chicken breasts.
Sprinkle each breast with 1 tablespoon of the Parmesan cheese and place them in the prepared baking dish.
Bake the chicken uncovered until the internal temperature at the thickest part reaches 165°F, about 40-45 minutes.
When the chicken has about 10 minutes left in the oven, begin making the sauce.
In a nonstick skillet over medium-low heat, warm the reserved bacon grease slightly, but don't let it start sizzling or bubbling.
Whisk in the heavy cream until well combined. Continue whisking until the mixture starts to foam up at the edges of the skillet.
Add the cream cheese and whisk until smooth. Add the remaining 1 tablespoon of Parmesan, the garlic powder, salt, and pepper. Whisk until smooth.
Toss a few bacon pieces into the sauce, but reserve enough to top the finished dish.
After the chicken is fully cooked, remove it from the oven, loosely tent it with foil, and let it rest in the baking dish for 5-10 minutes.
Transfer each breast to a plate, top each with 2-3 tablespoons of the sauce and a few bacon crumbles, and serve immediately.