Preheat the oven to 450 degrees F (230 degrees C).

Place bacon in a large, deep skillet over medium-high heat. Cook, stirring occasionally, until lightly browned but still soft, about 5 minutes. Drain on a paper towel-lined plate. Set aside.

Coat a large baking dish or cast iron skillet with 1 tablespoon olive oil. Arrange lemon slices in a single layer on the bottom of the prepared baking dish.

Stir together remaining 5 tablespoons olive oil, lemon juice, garlic, kosher salt, and black pepper in a large bowl until marinade is well combined.

Add Brussels sprouts to marinade in the bowl; toss until evenly coated. Use a slotted spoon to place Brussels sprouts over lemon slices in the baking dish, draining excess marinade back into the bowl. Scatter cooked bacon over Brussels sprouts.

Add potatoes to remaining marinade in the bowl; toss until evenly coated. Use a slotted spoon to arrange potatoes along the inside edge of the baking dish, draining excess marinade back into the bowl.

Add chicken breast halves to remaining marinade in the bowl; coat thoroughly. Place chicken, skin-side up, over vegetables in the baking dish. Pour any remaining marinade over chicken.

Bake in the preheated oven until chicken is no longer pink at the bone and the juices run clear, about 1 hour. An instant-read thermometer inserted near the bone should read 165 degrees F (74 degrees C).