Preheat your oven to 400°F.
Clean the mushrooms with a damp paper towel and halve them if desired.
In a small saucepan over low heat, melt the butter and add the minced garlic. Allow the garlic to infuse the butter for about 2 minutes without browning.
Place the mushrooms in a baking dish, drizzle with the garlic butter, season with salt and pepper, and toss to coat evenly.
Roast the mushrooms in the preheated oven for 15-20 minutes, stirring halfway, until they are tender and lightly browned.
While the mushrooms are roasting, season the chicken breast with salt and pepper. Grill or pan-sear the chicken breast over medium-high heat for about 6-7 minutes per side or until fully cooked and juices run clear.
Once cooked, slice the chicken breast into strips.
Plate the roasted mushrooms, top with the grilled chicken slices, and drizzle any remaining garlic butter from the pan over the dish.
Garnish with the fresh mixed herbs and serve immediately.