Start by pounding the chicken breasts to an even thickness of about 1.5 cm, then season generously with salt and pepper. Heat olive oil in a large skillet over medium-high heat, and sear the chicken until golden brown, about 3-4 minutes per side. Remove from the skillet and set aside.
In the same skillet, add butter and minced garlic, cooking until fragrant and just beginning to turn golden, about 30 seconds. Toss in sliced mushrooms, sautéing until they’re golden and earthy smelling, roughly 5 minutes.
Pour in the heavy cream, stirring to combine with the mushrooms and garlic. Add chopped thyme, and simmer gently for about 5 minutes until the sauce thickens slightly and becomes velvety.
Transfer the seared chicken breasts into a baking dish and pour the mushroom cream sauce evenly over the top, ensuring each piece is well coated. Sprinkle breadcrumbs over the sauce and scatter chopped parsley for freshness.
Bake in a preheated oven at 180°C (350°F) for 20-25 minutes, until the sauce is bubbly and the breadcrumb topping is golden and crispy.
Remove from the oven and let rest for 5 minutes. Garnish with additional chopped parsley and serve hot, spooning the creamy mushroom sauce over each tender chicken breast.
