1. Preheat oven to 200°C (400°F). Line a 30x41 cm (12x16 inch) rimmed baking sheet with parchment paper, extending the paper over the edges for easy removal. Lightly grease the parchment.

2. Melt the butter in a large saucepan over medium heat. Once fully melted, remove from heat and set aside.

3. In a large mixing bowl, combine the oats, sugar, flour, baking powder, and salt. Mix thoroughly.

4. Pour the dry mixture into the saucepan with the melted butter. Stir with a wooden spoon until evenly coated and a cohesive dough forms.

5. Transfer the dough to the prepared baking sheet. Using lightly greased hands, press it into an even, compact layer across the entire surface.

6. Bake for 12 to 15 minutes, or until the edges are lightly golden and the surface is set. Remove and let cool completely on a wire rack.

7. While the base cools, prepare the caramel layer. In a medium saucepan over low heat, combine the caramels and condensed milk. Stir continuously until melted and smooth. Pour this over the cooled oat base, spreading evenly with a spatula. Let set for 20 minutes.

8. In a heatproof bowl, melt the chocolate either in a double boiler or in the microwave in 30-second intervals, stirring between each until completely smooth.

9. Using the parchment overhang, lift the entire slab out of the pan and place on a cutting board. Cut into 12 rectangular bars.

10. Working one at a time, dip the top half of each bar into the melted chocolate at a diagonal angle, allowing excess to drip off. Place each bar on a parchment-lined tray.

11. Immediately sprinkle a few frozen raspberries over the wet chocolate before it sets. Let chocolate harden at room temperature or in the refrigerator for 10 minutes. Serve or store in an airtight container.