In a bowl, add the almond flour, coconut flour, baking powder, and sweetener of your choice. Whisk together, then set aside.
In a separate bowl, mix the wet ingredients, eggs, vanilla extract, lemon juice and zest, and greek yogurt.
Add the dry ingredients into the wet and mix with a stand mixer.
Divide batter among 12 paper-lined muffin cups. Bake in the preheated oven until a toothpick inserted into the center of the cupcake comes out clean, about 18 – 20 minutes.
Remove from oven and allow to cool several minutes in a muffin tin, then transfer to a wire rack to cool slightly.
Mascarpone Cheese & Vanilla Frosting
Whip the mascarpone and low carb powdered sweetener together in a bowl using a hand mixer.
Add 1/4 cup of the heavy cream, vanilla extract, then mix until smooth and creamy.
Add more of the heavy cream if needed, to get your desired consistency.
Transfer the frosting to a piping bag (ziplock bag with the tip cut off will work too), and frost once the cupcakes have cooled completely.