Preheat oven 350 F oven
In a large bowl whisk together flour, baking soda, baking powder, and salt. Cut cold butter into thin slices and add to flour. ( You could also freeze and grate). Using a pastry cutter, or two knives, begin cutting butter into smaller pieces into the flour. Feel free to use your fingers, breaking apart the butter into pieces no bigger than a pea. Having ununiform pieces is nice here. Add the pecans.
Whisk cream, sour cream, maple and vanilla in a small bowl. Stir this into the flour mixutre. Give it a few extra stirs, and if needed, add a few splashes of cream ( a tablespoon at a time) until the mixture forms a shaggy ball and all the loose flour is incorporated.
Place on a floured surface. Give the dough just a few kneads (15 seconds) then form a ball.
Flatten into a 7-8 inch disk or 6×9 inch rectangle, and shore up the edges, using a dough scraper or chef’s knife- so edges are straight up and down, and the disk is the same thickness throughout. Feel free to tuck more pecans into the top (just for looks).
Cut into 8-12 equal pieces. Place on a parchment-lined sheet pan, 2-3 inches apart.
Bake until beautifully golden, puffed and internal temp reaches 200F ( I highly recommend checking). Larger scones may take 30-35 minutes, smaller scones may take 20 minutes. So watch like a hawk!
While the scones are baking, make the Maple Glaze: in a little pot, heat the maple syrup. When warm, whisk in the powdered sugar until smooth. Add a pinch of salt. Turn off heat, leave on stove.
When the scones are done, let them cool for 15-20 minutes, then reheat the glaze and spoon a little over each one.