Cut 350 g chicken breast into cubes. Season with salt, pepper, and 1 pressed garlic clove. Refrigerate until ready to cook.
Heat 1 tablespoon olive oil in a large pan over medium-high heat. Fry the chicken cubes for 3-4 minutes until partially cooked (they will finish in the sauce). Remove and set aside. Add 100 ml water to deglaze the pan, scraping up browned bits. Pour the liquid into a bowl and reserve it.
In the same pan, add 1 diced onion and 1 pressed garlic clove. Fry over medium heat for 2 minutes. Add 125 g diced bacon and fry for 2 more minutes.
Add 1 diced bell pepper and 1 diced large zucchini to the pan. Fry over medium heat for about 7 minutes, stirring occasionally. Stir in 1 teaspoon tomato paste and sauté for 1 minute. Dice and add 1 tomato. Season with salt.
Pour the reserved deglazing liquid into the pan. Add 200 ml milk and 100 ml vegetable stock. Stir in 125 g sour cream, 2 tablespoons pesto, and 2 tablespoons balsamic vinegar.
In a shaker or jar, vigorously blend 50 ml milk with 2 tablespoons flour until smooth. Pour into the pan and stir well.
Increase heat to medium-high and bring to a boil, stirring frequently, for about 2 minutes until the sauce thickens. Chop and add 1 bunch basil. Return the reserved chicken to the pan.
Reduce heat to low and simmer gently for 5 minutes until the chicken reaches 74°C / 165°F internal temperature. Season to taste with salt and pepper. If the sauce is too thick, add water gradually; if too thin, stir in a little flour mixed with water.