Peel, core, and slice the apples evenly, about 1/4-inch thick.

Toss the sliced apples with lemon juice in a large bowl to prevent browning.

In a large saucepan, combine brown sugar, granulated sugar, cornstarch, cinnamon, nutmeg, and water. Stir and bring to a simmer over medium heat until it thickens.

Add the apples to the sauce and stir to coat well. Cook on low for 10 minutes until apples are tender but not mushy.

Remove from heat and stir in butter until melted and smooth.

Allow the filling to cool before using in pies or storing.