In a mixer using the paddle, cream the butter and sugar till light and fluffly.
Slowly mix in eggs one at a time.
Mix in vanilla.
Sift flour into a separate bowl, add salt, and baking powder. Mix well.
Alternate adding flour and milk. Add flour, then milk, then flour, then milk.
After batter is smooth drop into liners. Fill about ¾ way up.
Bake 20 - 25 minutes, till they pass the clean toothpick test.
Let rest till cool before frosting.
FILLING
Mix all the dry ingredients together in a saucepan.
Stir in egg yolks and milk.
Cook on medium heat while stirring often until liquid bubbles and thickens.
Remove from heat and stir in butter and vanilla.
Pour through sieve to remove the awkward bits. Use a spoon to help it along.
Chill in refrigerator.
BUTTERCREAM
Bring 1-2 inches water to a boil in a medium saucepan for a bain marie. Place a bowl over the pan. Water should be just below the bottom of the bowl.
Add egg whites and sugar to the bowl. Heat until mixture reaches 160 degrees F.
In a mixer bowl with the whisk equipped, beat until stiff peaks and room temperature.
Cut butter into tbsp size chunks. Mix in one by one. Keep mixing until smooth and glossy, may look worse before it gets better. If your icing is too warm, put in the fridge for 10-20 minutes.
Beat in vanilla and strawberry powder. (Powder is made by crushing freeze dried strawberries in a baggie. Sifted to remove hard chunks.)
Spoon frosting into an icing bag with desired tip.
Cut holes in cupcakes and fill with chocolate filling.
Pipe frosting on cupcakes.
Store in the fridge. Remove cupcakes from the fridge 20 minutes before serving.