Slice the chicken breasts into thinner strips for even cooking.
In a bowl, combine the chicken strips with garlic powder, paprika, smoked paprika, garam masala, black pepper, and ½ teaspoon salt. Mix well, then add the flour and toss until evenly coated.
Heat 2 tablespoons of olive oil in a large pan over high heat. Add the seasoned chicken and cook for about 8 minutes or until fully cooked. Remove from the pan and set aside.
In the same pan, add the remaining 2 tablespoons of olive oil, along with the onions and mushrooms. Sauté for about 5 minutes, until the onions are translucent and the mushrooms are tender. Add the minced garlic and cook for another 1-2 minutes until fragrant.
Pour in the half-and-half, season with the remaining ½ teaspoon salt and a little more black pepper, and stir to combine.
In a small bowl, dissolve the cornstarch in 3 tablespoons of water. Then, add 3 tablespoons of the hot milk mixture from the pan and stir well. Pour this mixture back into the pan, stirring continuously, until the sauce slightly thickens.
Return the chicken strips to the pan and let them simmer for a few more minutes, allowing the flavors to meld.