Peel and slice apples. Set aside until ready to cook.
In a large stove-top pot, melt the butter on medium-high heat.
Add the brown sugar, cinnamon, nutmeg, and salt until it is combined and become a lovely brown caramel color.
Add the apples to the pot, stirring to coat all of the apples.
Cook the apples on medium-high until they start to let go of some of their water and create more liquid.
When the liquid starts to boil (3-4 minutes), turn the heat down to low and cook the apples in the butter-sugar sauce for 15-20 minutes, stirring about 4-5 times during the cooking process.
In a small bowl or cup, combine the cornstarch and water, stir until smooth.
Fold the cornstarch water mix into the apples and gently stir until the sauce thickens.
Remove from the heat and cool at room temperature.