Line a sheet pan with parchment paper or spray a sheet pan with cooking spray. 

Combine the raisins and water in a microwave-safe bowl or cup. Cover with a small plate or plastic wrap. Microwave on high for 30 seconds. Remove from microwave, uncover and stir with a fork to loosen and separate. Set aside to cool.

Measure 1 cup of buttermilk and place it in the freezer while prepping other ingredients (you want it to be in the freezer for about 15 minutes).

Place butter in a microwave-safe bowl, cover with a paper towel and heat on high for 40 seconds. If not completely melted, return to microwave for 10-second intervals till melted. Set aside to cool.

For the cinnamon swirl, stir together cinnamon and sugar. Add the 1 tablespoon melted butter and water. Stir until combined. The mixture will be the consistency of wet sand. Set aside.

Whisk the flour, baking powder, baking soda, sugar and salt in a large bowl. Add raisins and stir to coat.

After the buttermilk has been chilled in the freezer for 10 minutes, combine it with the 8 tablespoons of melted butter (step 4). Stir with a fork until butter forms small clumps or globules. (See picture in the post.)

Add buttermilk mixture to dry ingredients and stir with a silicon spatula or wooden spoon just until all flour is incorporated. The dough will be fairly stiff.

Scatter the cinnamon sugar mixture over the top and, with a rubber spatula fold the dough from the bottom of the bowl over the cinnamon/sugar mixture on the top. Repeat. Don’t stir the dough, just fold it 3-4 times until it's incorporated in the dough in ribbons. You want the cinnamon/sugar mixture mixed into the dough, but it should be in raggedy ribbons throughout the dough.

Scoop dough up into 8 (or 12 for smaller biscuits) mounds on the prepared sheet pan. (I like to use a retractable ice cream scoop for this.)

Adjust the oven rack to the center of the oven and heat the temp to 400°F.

While the oven is preheating, place the sheet pan in the refrigerator for 15 minutes. (This will keep the biscuits from spreading out too much in the oven.)

Bake until tops are light golden brown and crisp, 14 to 18 minutes. Remove from oven and allow to cool, then drizzle with icing.

Combine powdered sugar, 2 tablespoons of milk and vanilla and whisk together until smooth. The mixture should be thick, but pourable. If too thick, add a little more milk.

Drizzle over biscuits in the desired amount.