1/4 cup unsalted butter, melted (half of one stick)
1 large egg
3/4 cup granulated sugar
1/4 cup light brown sugar, loosely measured
1 1/2 teaspoons vanilla extract
1 teaspoon cinnamon
1/4 teaspoon allspice
1/4 teaspoon ground cloves
1/4 teaspoon salt, optional and to taste
3/4 cup all-purpose flour
3/4 cup whole rolled old-fashioned oats (not quick cook or instant)
one 21-ounce can apple pie filling
one 9-inch frozen pie crust
caramel sauce, caramel ice cream topping.
ice cream or whipped topping, optional
Preheat oven to 350F. In a large microwave-safe bowl, melt the butter, about 1 minute on high power. Allow the butter to cool momentarily so you don't scramble the egg; then add the egg, sugars, vanilla, cinnamon, allspice, cloves, salt, and whisk to combine until batter is smooth (All spices and salt should be added to taste and use what you have on hand; omitting what you don't have and mixing and matching with other spices such as ginger or pumpkin pie spice is okay).
Add the flour, oats, and stir to incorporate. Fold in the apple pie filling. Pour filling mixture into frozen pie crust (I didn't bother pre-thawing it) and lightly smooth filling with a spatula. It's okay to fill pie crust up nearly to the brim; I did and it did not overflow. As insurance, place pie crust on a baking tray so if it does overflow a bit, it won't pool in the bottom of the oven. Bake for 50 to 60 minutes, or until top has just set and is not jiggly, and is golden. I baked mine for about 54 minutes and when I took it out of the oven, the filling had risen and was a bit domed and puffed, and as pie cooled, the dome sank and it flattened out. Allow pie to cool for at least 30 minutes before slicing and serving. Prior to serving, optionally drizzle with caramel sauce or serve with ice cream.
Pie should be kept covered and will keep in the refrigerator for up to 5 days; I prefer refrigerating it rather than keeping it at room temperature and I store my pie inside a large two-gallon sized plastic food storage bag in the refrigerator.