Generously grease the inside sides and bottom of 2 microwave safe mugs/ramekins. If you want to tip your cheesecakes out place a piece of baking paper on the bottom of your greased cup/ramekin, cut to fit the base. Grease the baking paper as well to ensure your cheesecakes will release more easily.
Gently combine the dry ingredients with the melted butter for the cheesecake bases. Don't over mix, keeping the mixture light in texture. Distribute the crumb mixture evenly between the two mugs/ramekins and press gently into the base. Note that if you press too firmly you may have trouble tipping your cheesecake out.
Add your cream cheese to a medium microwave proof bowl. Cover with paper towel and zap for about 15-20 seconds or until soft. Using a hand whisk, whisk until smooth and creamy, Whisk in the sour cream (or Greek yogurt) egg, lemon juice, sweetener and vanilla extract until really smooth. Distribute the cheesecake filling between the two mugs/ramekins and smooth out the tops.
Place mugs/ramekins spaced apart into a shallow microwave tray (glass/pyrex is great) and fill with boiling water about ⅔ of the way up the mug/ramekin. Cover the top of your mugs/ramekins with paper towel to preventing splatting.
Microwave on 850 watts (medium to high) for about 3½-4 minutes or until cooked through, rotating half way through. The edges of your cheese cake will be cooked but the centre may still be slightly soft. If the centre is too jiggly, cook again in short zaps until the centre has set. Remember that your cheesecakes will continue cooking on the bench so take care not to overcook. See notes for microwave oven tips.
Allow to cool at room temperature then place your cheesecakes covered with cling wrap in the fridge to cool and set for at least 1 hour prior to eating. This is vital to get the right creamy texture.
Notes
Like traditional cheesecake, this cake needs time to set to allow the flavors to develop and for the texture to settle. I don't recommend that you try to eat these immediately as they are initially too airy because of the cooking process. Refrigeration will resolve this and create a creamier texture.Switch the sour cream for yogurt ,Greek yogurt or marscapone.Use sweetener of choice such as monk fruit, stevia, xylitol, regular sugar or coconut sugar. It should equal to 2 tablespoons of regular sugar in taste, which is why 2 tablespoons of erythritol are used- it is 1 for 1.If you use too small a cup/mug/ramekin to cook in and your filling comes close to the top your filling may overflow when being cooked. Check that your mug/cup/ramekin holds at least 250ml/8 oz.Because all microwave ovens cook at different temperatures, you may need to play around with times and temperatures to get the cooking time and temperature correct. I use a Miele Microwave convection oven, and the times specified work well at 850 watts. Your oven might not give you options and may only cook at 600 or even 1000 watts. You will need to cook for as long as it takes to cook at a lower temperature and you may need to reduce the time to cook if your microwave is really high in watts.