In a large mixing bowl, combine the old-fashioned rolled oats, white whole wheat flour, light brown sugar, ground ginger, and kosher salt. Stir well to incorporate the dry ingredients, then mix in melted unsalted butter until the mixture forms clumps. Press about three-quarters of this mixture firmly into the bottom of a greased 9x9-inch baking pan to create a sturdy crust, leaving about ½ cup aside for the topping.

In a separate bowl, gently toss the small-diced strawberries with cornstarch, fresh lemon juice, and half of the granulated sugar. Once combined, evenly spread this fruity mixture over the crust in the baking pan.

Sprinkle the reserved crumb mixture over the strawberry layer, ensuring an even distribution.

Preheat your oven to 350°F (175°C). Bake the Strawberry Oatmeal Bars for about 35 minutes, or until the crust turns a lovely golden brown and the filling begins to bubble.

After baking, allow the bars to cool completely in the pan on a wire rack. Optional: Whisk together the powdered sugar with a splash of milk and drizzle over the bars before cutting into squares.