Prepare oven: Preheat oven to 400°F. Place a large rimmed baking sheet in oven while oven preheats.
Flatten chicken: Place chicken breasts between 2 sheets of heavy-duty plastic wrap, and flatten each to ½-inch thickness using a meat mallet or rolling pin. Discard plastic wrap, and transfer chicken to a sheet of parchment paper. Season both sides of chicken with salt and ½ teaspoon of the black pepper.
Make cream cheese mixture: Stir together cream cheese, Cheddar, and mayonnaise until smooth and well combined. Stir in bacon, hot sauce, garlic powder, 3 tablespoons of the scallions, 3 tablespoons of the almonds, and remaining ¼ teaspoon black pepper until evenly combined.
Top chicken with cream cheese mixture: Spread ½ cup of the cream cheese mixture on top of each chicken breast. Remove baking sheet from oven to a heat-proof surface. Carefully transfer parchment paper with chicken to preheated baking sheet.
Bake chicken garnish, and serve: Bake in preheated oven until cheese is melted and an instant-read thermometer inserted into thickest portion of chicken registers 165°F, 18 to 20 minutes. Remove from oven, and garnish evenly with remaining 2 tablespoons almonds and 2 tablespoons scallions.
