In a large mixing bowl, stir together flour, salt, 3/4 c. sugar, cinnamon, nutmeg, oats and soda together.
Add buttermilk, melted butter and vanilla. Gently stir to combine.
Stir in raisins and nuts if desired.
Pour in a greased slow cooker. Cook on low for about 2 hours 30 minutes. Times may be more or less depending on the size of your slow cooker and how hot it cooks. Watch the pudding and remove from slow cooker when it looks done. It should look like a moist cake. Try to leave the lid on while checking for doneness so steam doesn't escape.
When pudding is done invert on a plate to cool. Or serve with a spoon from the crock.
NUTMEG CREAM SAUCE:
Whisk together cornstarch and sugar. Add water and milk. Whisk.
Bring to a gentle boil over medium heat, whisking constantly. Boil for 1 minute.
Remove from heat. Add butter, vanilla, cinnamon and nutmeg. Stir.
Spoon or slice pudding. Serve with Nutmeg Cream Sauce. I like to serve this with equal amounts of sauce and pudding. I ALWAYS serve it warm. Whipping cream is optional, but necessary!! Sometimes I put pudding and sauce in a serving bowl about an hour before serving. The pudding soaks up the sauce and makes it extra moist. I add additional sauce when I serve the pudding!