Preheat oven to 400F. Line a baking sheet with parchment.
Combine the flour, 2 tbsp of sugar, baking power, baking soda, and salt in a large bowl.
Cut the butter into the flour mixture until coarse crumbs form.
Add yogurt to the flour mixture and stir until it starts to come together as a dough. Turn out onto a lightly floured surface and knead gently until the dough comes together.
Add a little more flour to the counter/table. Roll dough into a 20 x 30 cm (8 x 12 inch rectangle). See Notes, below.
Brush the dough with the melted butter, leaving a margin of a couple of centimetres (a little less than a inch) along one of the long sides. Sprinkle maple flakes on top of the butter.
Starting with the long side nearest to you, roll the dough up like a jelly roll. Pinch the seam along the bottom, then rock it gently back and forth to seal the dough. Cut into 2 1/2 cm (1-inch) slices, then lay on the prepared baking sheet.
Bake for 12-15 minutes until golden.
Let cool completely before icing. To prepare the icing, mix all icing ingredients together, then spread on the cooled swirls. (See Notes, below.) Sprinkle a few more maple flakes on top, if desired.