Preheat your oven to 350°F (175°C). Grease a 9x9-inch baking dish or line it with parchment paper for easy removal.
In a large bowl, combine the rolled oats, flour, brown sugar, salt, and baking soda. Stir until well mixed.
Pour in the melted butter and vanilla extract. Mix until the dry ingredients are fully combined and crumbly.
Press about two-thirds of the oat mixture into the bottom of the prepared baking dish to form a crust.
In another bowl, combine the raspberries, lemon juice, cornstarch, and granulated sugar. Gently toss to coat the raspberries.
Spread the raspberry mixture evenly over the crust in the baking dish.
Crumble the remaining oat mixture over the top of the raspberries.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and the raspberries are bubbling.
Allow the bars to cool completely in the pan before cutting into squares.