Set a rack in the middle of the oven and preheat to 425F.
In a large mixing bowl, combine flour, baking powder, baking soda, sesame seeds, sugar, black pepper, salt, and chopped scallions.
Using a cheese grater, grate the butter on a piece of parchment paper. Transfer the butter to the bowl and toss until coated in the flour, breaking up any larger chunks with your hands.
Make a well in the center of the bowl, and add in the skyr into the well. Slowly incorporate the skyr into the flour until a rough, slightly sticky dough forms.
Transfer the dough to a dusted surface, and pat into a rectangle, about 1 inch thick. Fold the dough in thirds, like a letter, then pat down into a rectangle shape again. Fold the dough, once more, in thirds, then pat down into a rectangle. Cut into 8 equal rectangles with a knife or bench scraper. Top with flaky salt.
Transfer biscuits to a parchment-lined baking sheet, and bake in the oven for 15 to 20 minutes, or until deeply golden-brown on both sides.
Meanwhile, prepare the gochujang maple butter. In a small bowl, mix butter, maple syrup, and gochujang paste until homogeneous. Heat in the microwave for 15 to 20 seconds, or until warmed through. Season with salt as needed and set aside.
Remove biscuits from the oven and allow to cool slightly, about 5 minutes. Serve warm with gochujang maple butter.