Preheat and Prepare: Preheat oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving overhang for easy removal.
Make Base Layer: In a large bowl, combine 2 cups flour, 1/2 cup granulated sugar, and salt. Cut in 1 cup cold butter until mixture resembles coarse crumbs. Press firmly into prepared pan. Pre-bake for 15-20 minutes until lightly golden.
Prepare Strawberries: While base bakes, toss sliced strawberries with 1/4 cup sugar, 2 tablespoons flour, and lemon juice. Let sit for 10 minutes to release juices.
Make Crumb Topping: In a clean bowl, combine 1 cup flour, brown sugar, 1/4 cup granulated sugar, and cinnamon. Cut in 1/2 cup cold butter until mixture forms clumps when squeezed.
Assemble Bars: Spread strawberry mixture evenly over pre-baked base. Distribute crumb topping evenly over strawberries without pressing down.
Final Bake: Bake for 35-40 minutes until crumb topping is golden brown and strawberry juices bubble around edges.
Cool and Serve: Cool completely in pan for 2-3 hours before cutting into squares. Serve at room temperature with whipped cream if desired.