Heat oven to 350F, placing the rack in the center.
Grease a 9x13 baking dish with non-stick spray and evenly spread the pie filling on the bottom (note: if using fresh fruit, add in now).
Sprinkle cake mix over top as evenly as possible then place butter slices over the cake mix (do not mix the layers).
Bake for about 30-40 minutes, or until bubbling and golden.
Allow it to sit for a few minutes and serve warm.
Notes
Don’t Mix the Layers: Keep the layers separate for the best texture.
Watch for Golden Brown: Bake until the top is golden and the strawberry filling is bubbling.
Unbaked Look: It is normal to have some unbaked cake mix on top, if you want to crisp that up, you can add extra butter to those areas as soon as you notice them and keep baking based on the recipe instructions (I like to look around the 20 minute mark).
Let It Rest: Allow the cake to sit briefly before serving so it sets slightly.
Even Cuts: Cut the butter into small squares and spread evenly so the cake mix bakes up golden.
Refrigerator: Store in an airtight container for up to 3-4 days.
Freezer: Once cooled, place in a freezer-safe container for up to 2-3 months.
Reheating: Thaw in the fridge overnight and rewarm in an oven slowly.