Preheat oven to 450º F(230ºC). Spray 6-cup muffin tin with nonstick cooking spray.
Pour strawberry muffin mix into a medium size mixing bowl. Cut in butter and stir in rolled oats. Divide evenly into muffin tin and press into the bottom. Bake 15-18 minutes until toothpick inserted comes out clean. Remove from oven and allow to cool completely.
Place one muffin crust into bottom of a small cup or bowl. Top with whipped topping and sliced strawberries and blueberries.
Refrigerate until ready to serve.