Preheat oven to 375 degrees F. Line a large baking sheet with parchment paper or a baking mat.
In a food processor, combine Pamela's Biscuit & Scone Mix and chilled dairy-free butter by quickly pulsing 6-8 times or until butter is just incorporated into the mix.
Add sugars, nutmeg, and cinnamon and pulse 3-4 more times. Add pecans, but do not pulse again!
In a large bowl, mix dairy-free eggnog and vanilla. Add the dry mixture to the wet mixture and gently stir just until combined.
Turn the dough out onto your baking sheet and knead just a few times with your hands, and then form into a circle - about ¾ inch thick and 8 inches in diameter. Cut the circle into 8 wedges using a knife.
Bake for 25 minutes, or until golden brown and cooked through.
While the scones cool, make the icing by combining the powdered sugar, nutmeg, and eggnog and stirring vigorously until no lumps remain.
Once the scones are completely cool, brush the icing on each scone, and top each scone with one whole pecan, if desired.