Arrange racks in upper and lower thirds of oven; preheat to 400°. In a cold, large, stainless steel or cast-iron skillet, arrange bacon in a single layer. Cook over medium heat, stirring occasionally, until crispy, about 10 minutes.
Remove skillet from heat and transfer bacon to a paper-towel-lined plate to drain. Pour off all but 2 Tbsp. bacon fat.
Reserve 2 Tbsp. cooked chopped bacon for serving. Transfer remaining bacon to a medium bowl. Add white scallion parts, cream cheese, almonds, mayonnaise, 3/4 cup cheddar, 1/2 tsp. salt, and 1/2 tsp. pepper and mix until combined. In another medium bowl, mix breadcrumbs, butter, and remaining 1/4 cup cheese until combined.
Return skillet to medium heat. Pat chicken dry; season all over with garlic powder, paprika, and 2 tsp. salt. Once pan is hot, cook chicken in bacon fat, undisturbed, until bottom side is golden brown, about 5 minutes. Flip chicken and top with cream cheese mixture. Top cream cheese mixture with breadcrumb mixture.
Bake chicken on lower oven rack for 15 minutes.
Turn on broiler. Move skillet to upper rack. Broil, watching closely, until cheese is melted and breadcrumbs are starting to brown, 3 to 4 minutes.
Transfer chicken to a platter. Using a dry kitchen towel or pot holder, return skillet to medium heat on the stovetop. Sprinkle with flour and whisk until combined and gravy is starting to thicken, 1 to 2 minutes.
Return chicken to sauce in skillet or spoon sauce over chicken on platter. Top with green scallion parts and reserved 2 Tbsp. bacon.
