1. Add apples, lemon juice, brown sugar, granulated sugar, cinnamon, nutmeg, and salt into a large saucepan. Stir together thoroughly and let rest for 10-15 minutes at room temperature. Add 3/4 cup of apple juice to the pan and stir.
2. Turn the heat to medium and cook the apple mixture, stirring often to make sure the apples cook evenly. Cook until apples have softened, about 10-14 minutes. Do not cook off all of the liquid. May need to add a little more apple juice.
3. In a small mixing bowl, create a slurry using the cornstarch and remaining 4 tbsp. apple juice. Whisk thoroughly.
4. Pour the slurry into the apples and stir together, until mixed evenly. Continue cooking until the apple mixture thickens, about 2-4 minutes.
5. Remove from heat and add butter and vanilla extract.
6. Scoop warm apple filling mixture into ramekins and serve with a scoop of vanilla ice cream on top.

NOTE: You can also let the mixture cool completely before making a pie or storing it in glass containers. This recipe yields about 6 cups and will last a week in the refrigerator or 3 months in the freezer.