In a food processor, add cottage cheese, sugar, buttermilk, 4 tablespoons melted butter and vanilla. Process until smooth. Add flour, baking powder, baking soda, and salt. Pulse just until the dough clumps together - don't let it form a ball. Scoop the mixture onto a floured surface and knead a couple times to smooth it out.
Roll the dough into a large 12" by 15" rectangle. Using a pastry brush, coat the top of the dough with the remaining 2 tablespoons of melted butter, leaving a 1/2" border on all sides.
To make the filling: In a small bowl, stir together brown sugar and cinnamon - scatter over the melted butter and gently press down to adhere. Sprinkle coconut over the sugar mixture.
Carefully roll up the dough, starting at the long edge, in a jelly-roll fashion. Pinch seam to seal while leaving the ends open. Using a sharp knife or a piece of unflavored dental floss, cut roll into 12 equal portions. Place the rolls into a 9" x 9" baking pan coated with nonstick spray.
Bake until golden brown and firm - about 25 to 30 minutes. Remove from the oven and let cool for about 5 minutes. Carefully invert the rolls onto a wire rack so the tops are still right-side-up.
To make the icing: In a small bowl, stir together confectioners' sugar, 3 teaspoons buttermilk and vanilla until smooth and icing has a thick, pour-able consistency. Add a touch of milk at a time until it gets to this consistency. Drizzle icing over the rolls.