Preheat the oven to 425°. Line a large, heavy baking sheet with parchment paper. In a food processor, pulse the brown sugar with the 2 tablespoons of softened butter and 1 teaspoon of the cinnamon until soft crumbs form. Transfer the mixture to a bowl.
In the processor, combine the 3 cups of flour with the granulated sugar, baking powder, salt and the remaining 1/4 teaspoon of cinnamon and pulse to blend. Add the cold diced butter and pulse until the mixture resembles small peas. Transfer the mixture to a large bowl and make a well in the center.
Add the cream, egg and vanilla to the well and stir to combine. Using a wooden spoon, gradually stir in the flour mixture until a firm dough forms. Crumble the brown sugar mixture over the dough and knead it into the dough, leaving some streaks.
Lightly dust a work surface with flour. Turn the dough out onto it and knead 3 times. Pat or roll the dough into an 8-inch round, about 1 inch thick. Cut into 8 individual wedges, then transfer the scones to the baking sheet and refrigerate for 20-30 minutes (may be frozen and and baked directly from the freezer). Bake for 18 to 20 minutes or until browned. Let cool slightly on the sheet, then transfer to a wire rack.
In a medium bowl, beat the cream cheese with the lemon juice. Beat in the confectioners' sugar until smooth. (Note: If the icing is too thick, add about 1 tablespoon milk). Spread the icing over the warm scones.