Preheat oven to 425°. Spray a rimmed baking sheet with cooking spray.
Using a sharp knife, cut off ends of potatoes (for a base for canapés). Cut potatoes in half shortways.
In a large bowl, toss together potatoes, 1½ teaspoons olive oil, parsley, ¼ teaspoon salt, pepper, and garlic powder. Arrange potatoes in a single layer on prepared pan.
Bake until potatoes are tender when pierced with a fork, approximately 15 minutes. Let cool completely.
Using a sharp knife, butterfly filets. Rub with remaining 1½ teaspoon salt.
In a medium cast-iron skillet, heat remaining 1½ teaspoons olive oil over medium-high heat. Add filets and cook until browned, 2 to 5 minutes per side. Transfer filets to a cutting board, and let rest for 20 minutes. Using a sharp knife, cut filet into 24 thin slices.
Stand potatoes larger ends up. Fold a filet slice in half and place on top of each potato. Top each with a blue cheese wedge.
Garnish with fresh parsley, if desired.
Notes
To prevent crumbling, freeze blue cheese for 1 hour before cutting into small wedges.
MAKE-AHEAD TIP: Potatoes and filets can be cooked separately a day in advance, cooled, and stored in airtight containers in the refrigerator. Let come to room temperature before using.
Recipe by TeaTime Magazine at https://teatimemagazine.com/blue-cheese-filet-rose-potato-canapes/