To toast the pecans, preheat oven to 350°F. Coarsely chop all pecans into small pieces; place on baking sheet and toast in the oven for 4 – 5 minutes until fragrant. Let cool.
Preheat oven to 375°F.
Whisk together the flour, sugar, baking powder, and salt in a bowl or processor.
Cut the butter into the flour mixture or process until it resembles pea-sized crumbs.
Add 1/2 cup of the cooled pecans into flour mixture. Toss to coat.
In a separate bowl, whisk together the sour cream, egg, and vanilla until combined.
Fold the wet mixture into the dry mixture with a spatula until combined. You may need to use your hands to finish mixing. Wrap the dough in plastic and refrigerate for 30 minutes.
After dough is cooled, roll or press to 3/4-inch thickness, using a little of the gluten-free flour if needed. Cut scones out with a 3-inch round cutter or cut into 8 triangles. You can re-roll the dough once or twice.
Place scones on a parchment-lined baking sheet, 1 to 2 inches apart. Bake for 13 – 14 minutes until scones are golden on the tops and bottoms.
To make the glaze, add cream, powdered sugar, and molasses to a bowl and whisk together.
Let scones cool before glazing or drizzling. Sprinkle with extra toasted pecan pieces for garnish.