Preheat an oven to 350 degrees F (175 degrees C). Combine the panko, Parmesan cheese, parsley, salt, black pepper, and mustard powder in a bowl until evenly combined.
Melt the butter with the garlic in a skillet over low heat. Once melted, cook and stir the garlic for 5 minutes to flavor the butter. Pour into a mixing bowl once melted. Dip the pheasant pieces into the melted butter, then press into the panko crumbs. Place onto an ungreased baking sheet in a single layer. Sprinkle the remaining panko crumbs over the pheasant nuggets.
Bake in the preheated oven until the pheasant pieces are no longer pink in the center, about 45 minutes.