Preheat oven to 350°F. Spread pecans on a baking sheet in a single layer. Toast for 6 minutes, then sit aside to cool.
Increase oven temperature to 425°F. Line a large baking sheet with parchment paper, set aside.
In a medium-size mixing bowl use a whisk to sift together, flour, sugar, baking powder, cinnamon and salt.
Add cubed butter. Use a pastry blender or two knives to cut the butter into the flour until it resembles cornmeal. Make a well in the center.
In a separate bowl, whisk together heavy cream, egg and vanilla until combined. pour into the well.
Use a fork to gradually mix the wet into the dry ingredients. Add 1/2 cup pecans, mix evenly through the dough.
Turn out onto a lightly floured non-stick surface such as a silpat or wax paper. Press or roll into an 8-inch circle. Dip a knife into flour and cut into 8 equal wedges.
Place wedges 2 inches apart on baking sheet. Brush with remaining cream and sprinkle each with reserved brown sugar.
Bake for 16-18 minutes until golden. Cool on the baking sheet for 10 minutes.
Meanwhile, make the glaze. Combine ingredients in a small bowl adding more cream as needed to thin to your taste.
Remove scones to a cooling rack. Drizzle warm scones with glaze and sprinkle with 1/4 cup remaining pecans. Serve immediately.