Preheat your oven to 180°C and line a 20*20 cm square pan with parchment paper.
In a bowl, toss together the strawberries and cornstarch. Set aside.
In another bowl, mix all other ingredients except the chocolate. Stir until combined.
Reserve 1 cup of the crumb mixture for the topping and press the remaining crumb mixture in the prepared pan. Flatten it out with a spoon or spatula until even. Bake the crust alone in the preheated oven for 10 mins only.
Remove from oven, add the chocolate chunks on top of the baked crust, followed by the strawberries then finally top it all with the remaining crumb mixture. Press it with your hand a bit.
Bake in preheated oven for 30-35 mins until bubbling and a bit golden brown on top. Remove from oven and let it cool for another 10 mins before cutting.