Preheat the oven to 350 degrees F. and on low fan speed, if using a convection oven.
By hand in a large bowl, blend the butter pats with the flour, sugar, brown sugar, salt and baking powder until the butter has been combined. Add the blueberries, and mix well, being careful not to crush all the berries.
In second bowl with a whisk, blend the cream, half-and-half, and the egg. Stir in the flour mixture and mix until the dough comes together. This is our scone dough. Remove the scone dough from bowl and knead on floured counter, rolling 5 to 6 times, ensuring not to over blend; this will result in a tough dough. Divide the dough into 12 even triangular shape portions. Arrange on a cookie sheet and bake until the tops are slightly browned, about 15 to 20 minutes. Remove from the oven and transfer the scones to a serving platter.
Serve with clotted cream, flavored mascarpone or creme fraiche.