Whisk sifted 2 cups all-purpose flour, 1/2 teaspoon baking soda, 4 teaspoons baking powder, 1/2 teaspoon salt and 2 teaspoons granulated sugar together in large bowl.
Using a pastry blender or a fork, cut in cold 1/4 cup unsalted butter and cold 1/4 cup shortening until crumbly.
Add 2/3 cup sour milk or buttermilk and stir just until combined, do not over mix.
Using both hands that have been floured, gently knead dough in the bowl to form a large ball of dough (kneading 6-8 times).
Turn out onto floured surface and roll into a rectangle about 1/4” thick.
Brush the rolled dough with 3 Tablespoons unsalted butter, melted; sprinkle with cinnamon sugar mixture (1/2 cup granulated sugar, 2 teaspoons ground cinnamon. Starting at one end of the dough, roll dough together to form a log, like a cinnamon roll.
Cut the dough into 12 pieces and place on lined baking sheet, cut side up.
Bake at 425°F for 12-15 minutes, or until lightly golden around the edges.
Combine 1 cup confectioner's sugar with 3-4 teaspoons water to make a pourable consistency; drizzle glaze over slightly cooled biscuits.