a double boiler is simply a pot of water with a bowl sitting on top. this allows gentle heat bowl without scorching / burning.
1
Put the butter and all the chocolate chips and wait until they get melt up,lower the heat ( u can also microwave your buter and chocolate if you don't want to uae boiler.)
2
get another bowl and put the 4 eggs and mix it a little bit and add the sugar ,vanilla extract ,mix it together until nicely combined.
3
add the chocolate mixture mix it all together for a few minutes and add the flour,then mix it well.
4
spray the muffin pan with cooking oil or butter ,then fill the muffinpan and bake it for 8minutes .done