In a medium bowl, whisk together melted butter, maple syrup, brown sugar, cinnamon, nutmeg, and salt.
Pour this mixture over the sweet potatoes in the slow cooker, stirring gently to coat.
Cover and cook on low for 4-6 hours, until the sweet potatoes are tender when pierced with a fork.
About 30 minutes before serving, stir in the chopped pecans and vanilla extract.
Uncover and cook for an additional 30 minutes to allow the sauce to thicken slightly and the pecans to toast.
Gently stir the sweet potatoes, being careful not to mash them.
Serve hot, spooning extra sauce from the bottom of the slow cooker over the sweet potatoes. Enjoy!
Notes
You can also cook on High for 2-3 hours.Sweet potato size: Try to cut the sweet potatoes into uniformly sized chunks to ensure even cooking.Sauce thickness: If you prefer a thicker sauce, you can transfer it to a saucepan after cooking and simmer it on the stovetop to reduce it further.