Preheat your oven to 350°F. Line a baking sheet with parchment paper.
In a medium bowl, whisk together the egg, sour cream, vanilla, stevia, and salt. Using a rubber spatula, mix in the almond flour and baking powder. The batter should be thick, as shown in the photo. If it's thinner than this, add ½ ounce (2 tablespoons) of almond flour.
Using a 4-tablespoon scoop, place 4 mounds of the batter on the prepared baking sheet, spacing them 2 inches apart. Very lightly flatten the tops, not too much, or they'll be too flat to slice.
Bake until golden, for 15-18 minutes. Turn the oven off, remove the biscuits, and place them in the fridge on paper towels to quickly chill them while you make the filling.
Make the filling and topping:
Cut two of the strawberries in half. You'll use these four halves to top the cakes. Slice the remaining strawberries into ⅛-inch slices.
Place the whipping cream, vanilla, and stevia in a mini food processor bowl. Process them on high (if you have a "grind" and a "chop" setting, use the "chop" setting) until the mixture turns into whipped cream, 30-60 seconds. Make sure not to over-process. ¾ cup of liquid cream should yield about one and a half cups of whipped cream.
Carefully slice each biscuit horizontally. Arrange 4-5 strawberry slices on the bottom half. Spoon about ¼ cup of whipped cream on top of the strawberries. Top with the second biscuit slice. Garnish with a dollop of whipped cream and a halved strawberry. Repeat with the three remaining biscuits.
Serve immediately, or keep the cakes at room temperature for up to an hour before serving.
Video
Notes
The food processor makes excellent, thick whipped cream – no elbow grease required. But since it’s so efficient, keep an eye on it and try to avoid over-whipping. A standard-size food processor likely won't work here though, since the amount of cream is relatively small.
If you don't have a mini food processor, you can whip the cream the old-fashioned way, in a cold mixing bowl using a handheld electric whisk with cold attachments. If you go this route, whip the cream until it starts to thicken, then add the vanilla and stevia and continue to beat until firm, taking care not to overbeat.
Flat biscuits are usually the result of batter that is too thin. See the photo in step 2 above - the batter should be thick, and the biscuits should hold their shape on the pan and not spread at all before they are put in the oven. If your batter seems thinner than the one shown, add an extra ½ ounce (2 tablespoons) of almond flour.
I don't recommend keeping leftovers of this cake. They will become soggy. I recommend making this dessert no more than an hour before you plan on serving it and only making as much as you (and your family or friends) can finish right away.