Preheat oven to 425°F. Spread 2 tablespoons butter in the bottom of a 9-inch pan.
Filling
With a fork, mix ½ tablespoon cinnamon and 2 tablespoons of butter.
Dough
Whisk together the flour, sugar, baking powder, baking soda, and salt.
Add 2 tablespoons melted butter to the buttermilk and whisk to combine.
Add buttermilk mixture to the flour and mix together with a spoon until liquid is absorbed.
Transfer the dough onto a lightly floured work surface and knead about 10 times working a little more flour into the dough until it's not sticky and the dough becomes smooth.
Roll dough or pat the dough into an approximately 9x12 rectangle. The dough will be thin.
Spread the cinnamon filling mixture over the top. Then spread the blueberry jam over the mixture and spread evenly.
Starting with the long side of the dough, roll dough jelly-roll style to form a long tube. Pinch the edge to seal. Using a sharp knife, slice into 8 to 10 equal rolls.
Place rolls in prepared 9-inch baking pan. Bake rolls 23 to 25 minutes or until the top is lightly browned.
If you're making the icing, make it now while rolls are cooking. Spread the icing over warm rolls and serve hot.