Preheat the oven to 375 F
lightly grease a 9-inch skillet or round baking dish
Peel, core, and dice the apples into ½” thick pieces. As you dice them, place the chopped apples in a large bowl and toss them with the lemon juice to prevent browning
in a medium bowl, mix together the melted butter, flour, sugar, cinnamon, nutmeg, and salt until it creates a thick paste
Transfer the sugar mixture to the bowl of apples and toss to coat
Spoon the apple mixture into the prepared baking pan, spreading evenly
put the flour, brown sugar, and salt in the bowl of a food processor fitted with a chopping blade
cut the cold butter into the bowl as well
place the lid on the processor and pulse to chop until it looks like coarse crumbs
remove the blade from the processor and add the oatmeal and press together until the oatmeal is incorporated
sprinkle the topping mix over the prepared fruit
bake in the preheated oven 45-50 minutes or until the fruit is bubbling hot and the topping is crispy brown
cool 10 minutes or so before serving with ice cream
OR cool completely a store lightly covered after 24 hours