Preheat the oven to 175 degrees Celsius. Line 24 cupcake moulds with cupcake liners. Set aside.
Sift the all-purpose flour, bicarbonate of soda and baking powder twice. Set aside.
Place the unsalted butter in a medium bowl. Using an electric mixer, beat the butter until creamy, for 30 seconds. Add in 1/3 of the caster sugar and beat on medium for 1 minute. Scrape the sides and add in half of the remaining caster sugar and beat on medium for another minute. Scrape the sides and add in the remaining caster sugar and beat for 1 minute on medium then another 2 minutes on high. Scrape the sides. The mixture will be pale in colour and fluffy.
Add in one egg. Beat on medium for 30 seconds and on high for another 30 seconds until the egg is incorporated. Scrape the sides. Repeat for the second egg.
Add in the vanilla extract and strawberry yogurt beat on medium for another 30 seconds. Add in the mashed strawberries and beat on low for 30 seconds until incorporated.
Fold in the flour mixture gently in two parts. Stir in red food colouring if like.
Divide the cake batter into 24 portions and bake for 12-15 minutes, until a skewer inserted into the center of the cake comes out clean.
If you bake for too long, the top will turn brown and a slightly hard crust will form at the top (that's what I experienced). If the top of the cake is turning brown, cover the top with an aluminium foil so that the top remains pink in colour. Remove the cupcakes from the cupcake moulds and let them cool on a wire rack completely.
Frosting
Place the cream cheese and the unsalted butter in a large bowl. Using an electric mixer, beat the cream cheese and butter until creamy, for 1 minute. Add in 250 grams of icing sugar gradually, beating constantly on medium speed. Add in the mashed and drained strawberries and lemon juice if using and beat on low to incorporate. Beat in the remaining 150 grams of icing sugar until desired sweetness and consistency is reached (you may not need to use the remaining 150 grams).
Pipe or pile the frosting on top of the cooled cupcakes and serve.
The cupcakes can be kept for up to 3 days in an air tight container in the fridge (due to the presence of fresh fruits used). Let the cupcakes warm up to room temperature or slightly colder than room temperature before consuming.
NOTES
To bake a cake: Prepare 2 7-inch round cake pans. Grease and line the bottom of the cake pans with parchment paper. Divide the cake batter between the two cake pans and bake for 20 - 25 minutes until a skewer inserted into the center of the cake comes out clean.