In a small bowl, stir the flour, brown sugar and cinnamon for the crumb topping, then drizzle in the melted butter and mix with a fork until large clumps form. Chill while you make the dough.
Blend the cottage cheese until completely smooth. In a large bowl, beat the softened butter and sugar for 2 minutes, then beat in the blended cottage cheese, egg yolk and vanilla until creamy.
Add the flour, protein powder, baking powder, baking soda and salt, and mix until a soft dough forms. Mix the brown sugar and cinnamon for the swirl, sprinkle it over the dough and fold just 2 or 3 times to create streaks.Cover and chill the dough for 20 minutes while the oven preheats to 350°F.
Line 2 baking sheets with parchment paper. Scoop the dough into 14 balls, about 2 tablespoons each, and flatten into 3/4 inch thick disks.Press a generous amount of crumb topping onto each cookie so it sticks well.
Bake for 12 to 14 minutes, until the edges are lightly golden and the crumb topping is set. Cool completely on a wire rack.
Whisk the powdered sugar and milk until smooth and drizzle over the cooled cookies. Let the glaze set for 15 minutes before serving.