Heat olive oil and bacon fat (or butter) over medium-high heat.
Season chicken with salt and pepper (use a light hand; you can always add more later!), and sprinkle and pat chopped rosemary over each side.
Add minced garlic and sauté for a minute or two, just until the garlic is slightly softened.
Add seasoned chicken to the skillet and cook for about 4-5 minutes on each side, depending on how thick your chicken thighs are. Cook long enough until you can see the chicken meat is cooked and until you get a nice sear on the skin.
Remove chicken and place on a plate; set aside.
Slowly add white wine to the skillet. Stir and gently scrape up any garlic or rosemary that have stuck to the pan.
Add half of the lemon slices (or quarters; whichever shape you wish!). Stir gently and cook for just 2-3 minutes, to soften them and flavor the sauce.
Add chicken back to the pan and use a spoon to pour the sauce over the chicken. Cook for just another minute or two more to warm up the chicken.
Garnish with remaining lemon slices and rosemary springs (optional).