Preheat oven to 160ºC (fan forced). Prepare muffin tin with paper liners.
Prepare Citrus Curd and set aside. Wash and dry TM bowl.
To make Cupcakes: Place sugar and zest into TM bowl and mill 10-15 sec/speed 9.
Add butter and chop 5-10 sec/speed 7. Scrape down sides of bowl and insert Butterfly. Cream mix for 1 min/speed 4.
Add half the flour and continue to beat on speed 4. Reduce to speed 2 and drop eggs through lid onto rotating blades one at a time.
Add remaining flour and milk combined with lemon juice. Mix 20 sec/speed 4. Scrape down sides of bowl if necessary and beat another 20 sec/speed 4.
Drop a generous tablespoon of cupcake mixture into each cupcake liner. Using a teaspoon, dollop a small amount of Citrus Curd on top of cupcake. Cover with additional cupcake mixture but DO NOT OVERFILL.
Bake for 20-25 minutes. Transfer cupcakes to cooling rack to completely cool before icing.
To make Icing: Place flour and milk into TM bowl and blend 5 sec/speed 6. Cook 15 min/80ºC/speed 4. Pour into bowl, cover with plastic wrap, pushing plastic completely down onto surface of mixture. Cool completely.
In clean and dry TM bowl, add sugar and mill 15 sec/speed 9. Add butter and chop 5-10 sec/speed 7. Insert butterfly and aerate butter and sugar 1-2min/speed 3/MC off. Scrape down sides of bowl as necessary.
Add vanilla and beat 6 sec/speed 4. Add cooked and cooled milk mixture and continue to beat for around 2-3 minutes/speed 3 until very smooth and white. Cover and refrigerate for 15 minutes (no longer and no less!) Ice cupcakes immediately.
Makes approximately 20 cupcakes.