Heat a griddle or large skillet over medium heat. Cook bacon until crisp then remove to paper towel to drain. Pour almost all the bacon grease into a bowl, leaving a little for cooking the burgers.
In a bowl, combine the turkey, 1 tablespoon bacon grease, garlic powder, paprika and grated onion. Gently mix together until just combined. Form into 4 balls and season generously with salt and pepper.
Place each ball of turkey onto the hot griddle several inches apart and immediately smash until thin. Only smash once. If you continue pressing as they cook, all the juices will release and leave the burgers very dry. Cook until browned and cooked through, about 2 minutes per side. Top with cheese and allow to melt.
To assemble burgers: spread bun with mayo, top with burger, bacon, lettuce, tomato and avocado.
