In a saucepan over medium heat, combine sugar and cornstarch, stirring until no lumps remain. Gradually add thawed raspberries to the mix, cooking for about 1-2 minutes until the mixture thickens and bubbles gently. Once ready, remove from heat and stir in almond extract for an extra burst of flavor. Allow the filling to cool while you prepare the crust.

In a large mixing bowl, combine quick-cooking oats, all-purpose flour, brown sugar, whole wheat flour, salt, and vanilla extract. Use a pastry cutter or your fingers to cut in the cold, cubed butter until the mixture resembles coarse crumbs.

Take 2-1/2 cups of the crumb mixture and press it firmly into a greased 9-inch square baking pan. Preheat your oven to 350°F (175°C) while you finish assembling.

Once the filling has cooled slightly, pour it evenly over the pressed crumb base in the baking pan. Use a spatula to spread it out smoothly.

Sprinkle the remaining crumb mixture over the raspberry filling evenly. Don’t press it down; just let it sit lightly on top to create that crumbly texture.

Slide the baking pan into your preheated oven and bake for 25-30 minutes, or until the top is golden brown and crisp.

Once baked, remove the pan from the oven and let it cool on a wire rack. After it has cooled completely, slice the Raspberry Oat Bars into squares or rectangles.