Preheat your oven to 325°F and lightly grease a 9×13 glass baking dish.
In a medium bowl, beat together the cream cheese, eggs, sugar, and vanilla extract until smooth and fluffy, about 2 minutes.
In a separate bowl, combine the canned strawberry pie filling with the thawed frozen strawberries, gently folding them together.
Spread the strawberry mixture evenly across the bottom of the prepared baking dish.
Pour the cream cheese mixture over the strawberries and use a knife to gently swirl it into the strawberry layer (don't mix completely).
Sprinkle the cake mix evenly over the previous layers, then sprinkle the brown sugar on top.
Grate the cold butter using a cheese grater with large holes and distribute it evenly over the entire surface (or cut into thin slices if preferred).
Cover loosely with foil and bake for 30 minutes, then remove foil and bake for another 25-30 minutes until the topping is golden brown and the filling is bubbling.
Allow to cool for at least 20 minutes before serving.
Serve warm or chilled, garnished with fresh strawberries and mint leaves if desired.