Add the butter, almonds, and rice to a saucepot and heat over medium. Cook and stir the rice and almonds in the melted butter for 1-2 minutes, or until they begin to smell toasty.
Add the cinnamon and nutmeg to the pot and continue to stir and cook for 30-60 seconds more.
Add the milk, sugar, vanilla, and salt to the pot and stir to combine. Allow the mixture to come up to a simmer over medium heat, stirring occasionally.
Once simmering, turn the heat down to medium-low. Continue to simmer the rice without a lid, stirring occasionally, for about 40 minutes, or until the rice is very soft and the mixture has thickened considerably. The pudding will thicken further as it cools.
Serve it warm or refrigerate and serve cold the next day.
*You can use the rice and milk of your choice. See the notes above the recipe for more information.*To use leftover cooked rice in this recipe, use 2 cups of cooked rice and 2 cups of milk.