Preheat your oven to 450º. F.
Use some spray olive oil to coat the roasting pan lightly.
Using the flat of your chef knife or a mortar and pestle, mash 4 garlic cloves with salt into a paste. Whisk the garlic paste together with lemon juice and 4 tablespoons of the olive oil. Season to taste with salt and pepper.
In a lightly oiled shallow baking pan, make 4 beds with overlapping lemon slices. On each bed, place a chicken breast half, skin side up. Brush each piece of chicken with a bit of the garlic-lemon mixture, reserving about half for later, and season very lightly with salt and pepper.
Quarter potatoes and toss with tomatoes, remaining 6 garlic cloves and 1 tablespoon olive oil until well coated. Season with a pinch of salt and pepper.
Arrange vegetables around chicken and add olives and rosemary.
Roast chicken and vegetables for 15 minutes, then brush with remaining garlic-lemon mixture, and roast for another 10 to 15 minutes until chicken is done. The internal temperature should be 162º F. Remove from oven, cover loosely with foil and let rest for several minutes, until the internal temperature reads 165º F.
Discard lemon slices and serve chicken with vegetables, spooning pan juices over them.
To get a bit fancier, pour off the pan juices and reserve. Add 1 tablespoon olive oil to the roasting pan. On the stovetop over medium-high heat, stir in 1 tablespoon of flour and cook, stirring for two-three minutes. Return the reserved pan juices to the pan and heat, stirring, until slightly thickened. Now you have a nice pan sauce to pass at the table or to spoon over the meat before serving.