Line a baking sheet with parchment paper - do not skip this step and do not use foil!
Combine sugars, butter, cream, nutmeg, and salt in medium saucepan and heat on medium. Stir constantly. Bring to a boil.
Reduce heat to low. Stop stirring and heat until thermometer reads 235°F.
Remove from heat.
Add the pecans and vanilla extract and stir until incorporated and mixture begins to thicken.
Pour out on baking sheet with parchment paper, a few tablespoons at a time. Space by a few inches.
Let cool at room temperature for at least an hour.
Store in a lidded container in the fridge or freezer.
Notes
Use parchment or possibly silicone on your trays. Foil WILL stick and you won't be a happy camper! You can easily peel the parchment off so your candy keeps its shape.
Always use a candy thermometer when making candy. You are looking for "soft ball stage" here which is 235-240°F.