In a bowl mix together berries, sugar, and cinnamon
Spread in bottom of pan
Sprinkle on ½ of the rolled oats, then cake mix, then remaining oats
Shave cold butter or pour melted butter evenly over the top
Bake for about 30 minutes until bubbly and golden
Serve with ice cream if desired and enjoy!
Notes
Toss the berries with a little sugar and let them sit for 10–15 minutes, or briefly warm them on the stovetop until they’re just starting to release their juices. This jump‑starts that jammy, bubbling filling and helps the cake mix hydrate more evenly as it bakes.
Do Not Stir: Dump cakes work best when the layers stay separate.