Set oven to 400 degrees F and move rack to the middle of the oven.
Place your pumpkin puree on a plate and use a paper towel to press out the juice. Repeat this about 4 times.
Freeze your butter and then grate it with a cheese grater or food processor. Place in the freezer until time to use.
Mix together your dry ingredients in a large bowl then remove half.
Add the grated butter to dry mixture and mix again.
Add the milk, sour cream, and pumpkin and mix until it's fully incorporated. You can use a mixer, dough whisk or your hands.
Add in the rest of the dry ingredients and mix just until it comes together.
Turn dough onto a floured surface and use your hands to press it into a ~9in. circle.
Cut the dough into triangles with a dough scraper.
Place triangles onto a greased baking sheet and place in the freezer for an hour or overnight.
Bake the scones at 400 degrees for 10 minutes, then rotate the plan and reduce heat to 375. Bake for an additional 16-20 minutes** (until firm and a toothpick inserted comes out clean).
Let them cool on the pan for 10-15 minutes, then remove and serve warm.
Mix butter, sugar and cinnamon together for the icing.
Drizzle in milk just until icing reaches a smooth consistency and can run off a spoon.
Use a spatula or spoon to drizzle the icing on top of the scones.
