Melt butter in a large skillet over medium heat.
In a large bowl mix together the chopped apples, 3 tablespoons water, and the sugar, cinnamon, cloves, and salt. Stir well to coat the apples evenly.
Cook the apple mixture in the melted butter over medium-high heat for 5–7 minutes until the apples begin to soften but remain slightly firm. Stir occasionally for even cooking.
In a small bowl, mix 2 tablespoons of the water with the cornstarch until smooth. This cornstarch slurry prevents clumps and ensures a thick, smooth apple filling.
Pour the cornstarch slurry into the apples in the skillet and stir constantly over medium heat until the mixture thickens and becomes glossy, just a few minutes.
Remove from heat once the apples are tender and coated in a thick, golden brown sauce.
Let the filling cool to room temperature before using in a pie dish or storing.