Start by making the Spiced Maple & Pecan Butter.
In a food processor, combine the pecans (or walnuts), vanilla, cinnamon, maple extract, and salt.
Process until smooth for a few minutes.
Use a spatula to scrape the mixture from the sides if needed.
Add Erythritol and butter (or coconut oil).
Pulse until smooth.
Transfer the dough to an 8 x 8-inch (20 x 20-cm) parchment-lined pan, or a silicone pan.
With a spatula, spread the dough evenly into the pan.
Add roughly chopped pecans and mix in.
Top with the remaining pecan halves.
Refrigerate for 1 to 2 hours, or until set.
Be sure the fudge has set before slicing.
Keep refrigerated for up to 1 week or freeze for up to 3 months.