Preheat the oven to 175℃ (350℉). Grease and/or line an 18cm (7") springform pan.
Heat the butter, just until most of it has melted. Set aside.
In a bowl (I used my stand mixer), add the egg and sugar substitute, and whisk until light and pale in colour.
Add in the butter, gräddfil, and milk and whisk just until everything pulls together.
In a separate bowl, combine the remaining dry ingredients (but not the dried raspberries), and gradually add to the wet ingredients, mixing only until everything is combined, and taking care not to overmix.
Crush the freeze dried raspberries and fold into the batter.
Pour into the prepared pan and bake for around 25-30 minutes until an inserted toothpick comes out clean.
Leave to cool in the pan for five minutes, then remove the outer edge of the springform.
While the cake is still warm, mix a little more of the substitute sugar and crumbled dried raspberries together and sprinkle over the top.
When completely cool, slice and serve. Enjoy!