• Preheat the oven to 350°F(177C°). Grease 8 inch (20cm) square oven-proof dish and line the bottom and sides with parchment paper, about 2 inches(5 cm) of overhang on each side.
• Chop the strawberries into small pieces. If the strawberries seem very juicy, put them on the paper towel to let them dry so if there is any excess liquid, it will be removed. Keep the strawberries aside.

Crust and Crumbles

• Place the flour and sugar in a big mixing bowl. Add in the cold butter pieces and cover with flour mixture. Rub them with your fingertips until the mixture looks like breadcrumbs.
• Put ⅔ of the dough into the oven proof dish and spread it evenly with a spoon. You may need to lightly flour the spoon to avoid it sticking to the flour-butter mixture.  Keep ⅓ of the dough in the bowl and store the bowl in the freezer until ready to use.

Filling

• Toss the chopped strawberries with sugar and cornstarch.  (If there is excess juice left in the bowl don't use it while covering the crust.)

Assemble

• Cover the crust with strawberries. Remove the bowl from the fridge and gently sprinkle and cover the strawberries with crumbles.
• Bake for 55-60 minutes until the top becomes golden brown and the crumbles are crispy. Let it completely cool before removing the bars from the dish. Once they are cool, lift the paper from sides, remove the bars from dish, cut into 16 pieces.