Peel, core, and thinly slice the apples into roughly ¼-inch thick slices. Toss with granulated sugar and lemon juice in a large bowl and let stand for 5 minutes to draw out moisture.

In a large pan over medium heat, melt the butter with the brown sugar, vanilla, cinnamon, salt, and a little water.

Add the apple slices and any accumulated juices from the bowl to the pan, cover, and cook for about 6 minutes until slightly softened.

In a small bowl, mix cornstarch with enough water to create a slurry.

Remove the lid and stir the cornstarch mixture into the apples. Bring to a light boil, stirring constantly, until thickened, about 1 more minute.

Remove from heat and cool slightly before using.