Arrange bacon on a aluminum foil lined cookie sheet.
Place each chicken breast between sheets of parchment paper and tenderize/flatten with a mallet or small sauce pan. Move chicken to a baking pan, drizzle each breast with 1 tbsp olive oil, coating both sides. Salt and pepper to your own taste or use a premixed seasoning.
Place bacon and chicken in the oven. Bake bacon for 10-12 minutes or until crisp enough to crumble. Bake chicken for 25-30 minutes or until cooked through and no longer pink in the center.
While the bacon and chicken bake, heat the remaining 2 tbsp olive oil in a skillet over medium high heat. Halve and slice the onion and mince the garlic. Add to the skillet once the oil has heated (shimmering). Cook onions and garlic until the onions have begun to turn translucent. Remove to a bowl.
Chop the asparagus into 1 inch pieces, set aside. (You only need to use the top two inches, discard the rest).
When the bacon is cooked, move to a paper towel for a minute or two to drain any excess grease. Crumble/break apart each piece and set aside.
When the chicken is cooked, remove from oven and let rest for 5-10 minutes or until cool enough to handle. Move to a cutting board and slice into bite size pieces.
Increase oven heat to 400.
Place two flatbreads per cookie sheet. Coat with a thin layer of pizza sauce. Place 1/4 of the chicken, onion mixture, bacon and asparagus on each flatbread. Top each with 1/2 cup mozzarella cheese.
Bake at 400 for 7-8 minutes or until the flatbread is crispy and the cheese melted.