Preheat your oven to 350°F. Spray an 8" x 8" glass baking dish with nonstick spray.
In a medium bowl, whisk together almond flour, baking powder, oat fiber, and salt. Set aside.
Separate eggs. Whip egg whites with a hand mixer until soft peaks form.
Add Swerve confectioners to egg yolks and mix until smooth. Stir in sour cream, vanilla extract, and vanilla bean paste.
Fold dry flour mixture into wet yolk mixture. Then fold in whipped egg whites until just combined.
Pour batter into prepared dish. Bake 30-35 minutes until toothpick comes clean. Cool completely on wire rack.
For frosting: Beat mascarpone and cream cheese together until smooth. Add 1/3 cup heavy cream, Swerve confectioners, and vanilla. Beat until creamy. Add more cream if needed.
Spread frosting evenly over cooled cake.
Arrange blueberries in top left corner for stars. Place strawberry slices in rows across cake. Sprinkle shredded coconut in empty rows to form white stripes.