Toss apple slices with lemon juice and set aside.

Combine water, maple syrup, vanilla, sugar, cornstarch, salt, cinnamon, and nutmeg in a large saucepan, stirring until well mixed.

Bring maple syrup mixture to a simmer over medium-high heat, stirring constantly until the sugar dissolves, and the mixture thickens and turns clear.

Fold in apple slices and return to a simmer.

Reduce heat to low and cook for 5 minutes.

Remove from heat and allow to stand for 15 minutes before spooning into a prepared pie crust or freezing.