Preheat the oven to 325F and lightly grease a 9×9 inch square pan.
In a medium bowl, whisk together the almond flour, sweetener, and salt. Stir in the butter until well combined.
Press firmly into the bottom of the prepared baking pan and bake 12 minutes. Let cool while preparing the filling and topping.
In a small food processor or blender, puree the raspberries until completely smooth. Press the mixture through a fine-mesh strainer, discarding seeds and pulp.
In a small pot, bring raspberries to a simmer. Dissolve the gelatine in boiling water, add to the filling mixture and mix well.
Let cool for 15 minutes and pour over the cheesecake filling.
In a small heatproof bowl set over a pan of barely simmering water, melt the white chocolate with the cocoa butter, stirring until smooth. Do not walk away, as white chocolate can seize very easily. Remove the bowl from over the heat once melted.
In a large bowl, beat the mascarpone cheese with powdered sweetener until smooth.
Add vanilla extract. Beat in the melted white chocolate. heavy cream and beat until just combined.
Put the gelatine powder and 4 tbsp of water into a small bowl. Microwave for 45 seconds. Add to the filling mixture and mix well.
Let refrigerate for 1 hour before adding the raspberry filling. Then add the raspberry filling and let refrigerate for 3 hours before serving.