Preheat the oven to 350°F.
Wash, peel and slice the apples into 1/2-inch to 1-inch pieces. Remove and discard seeds.
Place the cut apple into a large bowl.
Add in the lemon juice, brown sugar, cinnamon powder, nutmeg powder and salt.
Mix thoroughly.
Microwave the butter until melted (about 20 seconds).
Pour over apple pieces. Mix to combine.
In a small bowl, whisk cornstarch and water together to form a slurry. Add extra water if necessary for the cornstarch to be fully incorporated.
Pour over the apples. Mix fully.
Add the apple slices to a large baking dish. Cover with foil.
Bake in a preheated oven for 25 minutes.
Remove from the oven. Remove the foil.
Place the apples back in the oven to bake for another 20 minutes.
Remove and allow to cool.
Serve warm or cool.