In a large Dutch oven or stock pot add white sugar, brown sugar, cornstarch, salt, cinnamon and nutmeg. Whisk until combined. Add 6 cups water and whisk again until mixed well. Place pot onto stove (uncovered) on medium heat. Bring to a boil, then cook for 1 minute, whisking constantly.
Drain apples using a strainer and gently rinse with tap water.
Add apples to the pot of sugar and spices, and stir with a large spoon (wooden or nylon to prevent scratching the pot). When everything is mixed together, increase heat to medium-high and bring to a boil. You’ll know it’s boiling when you hear the first few plops of liquid between the apples, like bubbling lava. This should take around 5-6 minutes to get to boiling.
As soon as it starts boiling, reduce heat to medium-low. Cover and simmer, stirring occasionally, for 8-9 minutes or until apples are tender but still firm.
Remove from heat, uncover and let cool for at least 20 minutes, stirring every 5 minutes or so to help it cool quickly.
How to use it in apple crisp: In a lightly greased baking dish pour the filling into 8x8 pan. Top with apple crisp topping then bake as directed. Here is my recipe for the best ever apple crisp.
If you want to can this recipe I recommend not adding the apples after cooking the syrup. Drain the apples then mix them with 3 tablespoons fresh squeezed lemon juice. Pack the apples into about 7-8 quart sized jars, pour syrup into jars and use knife to remove air bubbles. Seal and process for 20 minutes in a water bath canner.