Combine almond flour, sweetener, baking powder, and pinch of salt in a 12-ounce mug or larger; stir to combine.
Stir in heavy cream, egg, melted butter, vanilla extract, and diced strawberries; stir just until everything is combined, but don't overmix.
Microwave on high for 90 seconds, or up to 2 minutes. Test for doneness, add a few seconds as necessary, but don’t overcook.
Remove from microwave and let cool a bit while you work on the whipped cream.
In a medium mixing bowl combine heavy whipping cream and sweetener; using your mixer, beat on medium speed until stiff peaks form. Taste for sweetness and adjust accordingly.
Top mug cake with 1 tablespoon prepared whipped cream and a strawberry; serve.