Place the steel-cut oatmeal in a large skillet over medium-high heat.
Toast the oatmeal, stirring constantly for 8–9 minutes, until it becomes fragrant and begins to brown around the edges.
Remove the oatmeal from the skillet and transfer it to the slow cooker.
In the same skillet, melt the butter and add the chopped walnuts.
Toast the walnuts over medium heat, stirring constantly, until they are nicely browned.
Add the toasted walnuts and all remaining ingredients (except the spices) to the slow cooker.
Cover and cook on low for 7–9 hours, until the oatmeal is tender.
Stir in the cinnamon and nutmeg, cover, and let the oatmeal stand for 10 minutes.
Serve topped with a bit of butter, maple syrup, brown sugar, and more chopped walnuts for extra flavor.
Notes / Tips / Wine Advice:
Serving Tip:Serve warm with your favorite toppings such as fresh fruit, nuts, or a drizzle of honey for added sweetness.Wine Advice:Pair with a light, crisp white wine, such as Sauvignon Blanc, for a refreshing contrast.