Place the steel-cut oats, almond milk, sliced peaches, brown sugar, cinnamon, vanilla extract, and salt directly into the slow cooker.
Stir everything together until the brown sugar and spices are evenly distributed.
Cover the slow cooker and cook on low for 6 to 8 hours, until the oats are soft and the peaches have released their juices.
Stir the oatmeal once more before serving, then divide into bowls and top each portion with chopped pecans.