Preheat oven to 475 degrees (if you have a dark baking sheet, lower by 25 degrees). Prep baking sheet by lining with 1 sheet of parchment paper. Set aside.
In a large bowl, add flour, salt, and baking powder. Grate butter using the shredding side of a box grater and place into the flour mixture. Toss together to combine. Place into the freezer for 10 minutes.
Remove from freezer and toss in blueberries until evenly combined with flour mixture. Create a well and pour in the buttermilk. Mix with a wooden spoon about 15 times around. Don't worry if it's not completely mixed.
Flour your kneading surface. Pour our biscuit mixture onto counter and work together with your hands until the mixture is no longer dry and crumbly. Flour your rolling pin and begin to roll out the dough into a rectangle until it's about 3/4-inch thick. Fold in half so the short edges touch. Rotate the dough and repeat this again 4 more times, adding flour as needed to prevent sticking. Roll out into one final rectangle that is about 3/4-inch thick.
Using a biscuit cutter, cut out biscuits and place on prepared baking sheet so that the biscuits are touching. Combine remaining scraps and roll out again (no need to repeat folding process) and cut more biscuits until all the dough is used.
Bake biscuits in a preheated oven for 13-15 minutes, or until they start to brown on the edges. Remove from oven. Let them cool for a few minutes.
Add heavy cream to powdered sugar and whisk until icing forms. Spoon a little over each biscuits to cover the tops. Serve immediately.