To prepare the chicken: In a bowl mix together olive oil, lemon juice, thyme leaves, mint leaves and garlic. Rub the mixture over the chicken and marinade for 30 minutes if you have time. Preheat oven to Gas Mark 6, 200°C (400°F) . Take three medium bowls and put the flour in one, the eggs and milk in another and the breadcrumbs in the third. Whisk the eggs and milk to combine. Lift the chicken out of the marinade and working one at a time, dust each chicken breast with flour, dip into egg mixture, then press into breadcrumbs, making sure each breast is well coated. Lay on a shallow baking tray lined with lightly oiled baking parchment, drizzle a little oil over the chicken and bake in the oven for 25 minutes. Mix the mayonnaise with the garlic, mustard and lemon juice. Taste, season and serve along with the chicken.