1. Mix egg, kefir, sweetener, flour and baking powder until smooth
2. Peel the apple and chop on a small cubes.
3. Sprinkle chopped apple by cinnamon, sweetener and add lemon juice - mix all together
4. Add apples to the dough and combine until smoot
5. Spread ceramic/silicon mold for baking by oil, transfer this mass here and cook for 2-3 min in a microwave (on high power) until ready.
6. Cool a little and serve with sour cream, syrup or melted chocolate

Preferably all ingredients should be room temperature.

You can use different kind of flour or change the kefir on a plant yogurt.

You can also use different kind of sweetener (sugar, honey, stevia etc).

Don't cook long time in a microwave - cupcake can be too dry.