In a bowl of a stand mixer with a dough hook attachment, combine fed sourdough starter, flour, sugar, warm milk, salt, and melted coconut oil. Mix together until it forms into a ball and the dough is pulling away from the sides.
Remove the dough and form into a ball and place in a large greased bowl. Cover tightly with plastic wrap to prevent the dough from drying out and let it set in a warm place throughout the day (or about 8-12 hours).
After the dough has doubled, transfer the dough onto a lightly floured board and divide it into four equal pieces. Roll out each piece into a circle about 9 1/2 to 10 inches in diameter, making sure the dough is around 1/8 inch thick. This will ensure you get the proper layering for your snowflake. *See note*
You should now have four circles of dough, each of equal size, ready to be layered.
To assemble your snowflake start by placing the first dough circle onto a piece of parchment paper or directly into your greased baking dish. Use a basting brush to spread a layer of melted butter across the surface of the dough, then sprinkle it with 1 1/2 tablespoons of sugar and sprinkle cinnamon.
Place the second dough circle on top of the first, aligning the edges carefully. Pinch the outer edge together slightly to help the circles stay together. Repeat the same process: brush with butter and sprinkle with sugar and cinnamon.
For the third circle, repeat the same steps.
Once you’ve stacked the three circles with cinnamon and sugar, place the fourth and final circle on top. DO NOT brush with butter or sprinkle sugar on this final layer.
To create the beautiful snowflake shape, place a 4 oz mason jar or small glass in the center of the circle and press lightly to make a circular impression in the center of the dough. This will be your guide when you cut the dough into wedges.
Using a dough cutter or sharp knife, cut the dough into 16 equal wedges, stopping at the circular impression in the center.
Now, take two adjacent wedges, twist them away from each other three times, and pinch the edges together. Repeat this process for all wedges to form the snowflake shape.
Once your snowflake is formed, cover it loosely with plastic wrap and allow it to rise for another 8-10 hours, or until it is puffy and doubled in size.
After the second rise it's time to bake! Preheat your oven to 350°F. Place your cinnamon roll snowflake into the preheated oven and bake for 23-25 minutes, or until the top is golden brown. Keep an eye on the snowflake to avoid overbaking, as it should be golden and slightly crisp on the outside, but soft and gooey on the inside.
Once baked, remove the snowflake from the oven and let it cool slightly before icing.
While the cinnamon roll snowflake is cooling, prepare the icing. In a small bowl, whisk together powdered sugar, milk, butter, and vanilla extract until smooth. If the icing is too thick, add more milk a teaspoon at a time until it reaches your desired consistency.
Transfer your potato flake sourdough cinnamon roll snowflake to a cake stand or platter for a beautiful presentation. Drizzle the icing generously over the warm cinnamon roll snowflake, or if you prefer a more delicate topping, you can thin out the glaze or dust with powdered sugar.