Oven Preparation: Begin by preheating the oven to 350 degrees Fahrenheit. Line an 8-inch square baking dish with aluminum foil, leaving a 2-inch overhang on two opposite sides to facilitate easy removal of the bars after baking. Once lined, apply a light coating of grease to the foil.

Dry Ingredient Mixture: In a large mixing bowl, combine the all-purpose flour, baking soda, and salt, whisking them together thoroughly. Add the rolled oats and light brown sugar to the mixture. Utilize clean fingertips to break up any clumps of brown sugar, ensuring an even consistency.

Incorporating Butter: Add the softened unsalted butter to the dry ingredients. Use your fingertips to blend the butter into the mixture until it is uniformly moistened. This mixture will form both the base and the topping of the bars.

Assembling the Base: Transfer approximately 2 cups of the oat mixture into the prepared baking dish. Press down firmly to create an even and consistent base layer.

Adding the Raspberry Layer: Spread the raspberry jam evenly over the oat base, maintaining a margin of about 1/4 inch from the edges to prevent the jam from seeping out during the baking process.

Final Layer and Baking: Sprinkle the remaining oat mixture over the raspberry layer and press down gently to form a crumbly top. Bake in the preheated oven until the surface turns golden brown, approximately 34 to 38 minutes.

Cooling and Serving: Remove the bars from the oven and allow them to cool completely in the dish. This step is vital for the bars to set properly. Once cooled, use the foil overhang to lift the bars out and cut them into desired sizes. Store the bars in an airtight container.