- Preheat your oven to 350°F (175°C) and grease a 9x9-inch baking pan or line it with parchment paper for easy removal. 
- In a large mixing bowl, combine the rolled oats, flour, brown sugar, baking soda, and salt. Mix well. 
- Pour the melted butter and vanilla extract into the dry ingredients and stir until everything is well combined and crumbly. 
- Press half of the oat mixture firmly into the bottom of the prepared baking pan to form a crust. 
- Spread the raspberry jam evenly over the crust. If using fresh raspberries, scatter them evenly over the crust instead. 
- Sprinkle the remaining oat mixture over the top of the raspberry layer, pressing it down gently. 
- Bake in the preheated oven for 25-30 minutes, or until the top is golden brown. 
- Allow the bars to cool in the pan for at least 15 minutes before cutting into squares. For best results, chill in the refrigerator for an hour before serving.