Preheat your oven to 350°F (175°C).
Line a 9x9 inch baking pan with parchment paper, leaving some overhang on the sides.
In a large mixing bowl, combine the whole wheat flour, old-fashioned oats, brown sugar, and salt. Stir well.
Add the cold unsalted butter cubes to the dry mixture. Cut the butter into the dry ingredients until it resembles coarse crumbs.
Drizzle in the cold water and mix until just combined, being careful not to overwork the dough.
Press half of the oat mixture firmly into the bottom of the prepared baking pan. Spread the fruit preserves evenly over the crust.
Crumble the remaining oat mixture over the fruit preserves, pressing it down gently.
Bake for 25-30 minutes, or until the top is golden brown and slightly firm to the touch.
Once baked, let it cool completely in the pan before using the parchment overhang to lift the bars out. Cut into squares or rectangles.
