Preheat over to 350 degrees F. Spread the pecans onto a baking sheet and place in preheated oven 7-10 minutes until fragrant. Shake the baking sheet halfway through baking so the nuts will toast evenly. Remove nuts from oven and set aside to cool completely.
In a large saucepan over medium heat, bring water and milk to a simmer.
In a large saucepot, melt the butter until it just begins to foam and then add the oats. Stir for 2 ½ minutes until golden and fragrant; set aside. Once the milk mixture is simmering, add the toasted oats and reduce heat to medium-low. Simmer uncovered without stirring until the mixture looks like gravy, about 20 minutes. Add salt and vanilla and stir lightly. Continue simmering, stirring occasionally, until almost all the liquid is absorbed and oatmeal is thick and creamy, 7 to 10 minutes. Turn off heat and let stand for 5 minutes.
Spoon into 4 bowls and top each serving with 1 teaspoon brown sugar, dash of cinnamon, 1 tablespoon chopped pecans, and half of a sliced banana.