I regularly write long nested Excel functions, is there an easy way to
convert a function that I have made work in Excel into a custom
function without having to rewrite the whole thing into VBA?

Here is an example function:

=IF(LEFT($A6)=TEXT(O$3,0),REPLACE(REPLACE(IF(LEFT( $A6)=TEXT(O$3,0),REPLACE($A6,1,1,""),""),1,FIND("
- ",IF(LEFT($A6)=TEXT(O$3,0),REPLACE($A6,1,1,""),"") )+2,""),FIND(" -
",REPLACE(IF(LEFT($A6)=TEXT(O$3,0),REPLACE($A6,1,1 ,""),""),1,FIND(" -
",IF(LEFT($A6)=TEXT(O$3,0),REPLACE($A6,1,1,""),"") )+2,"")),1000,""),"")

Any help would be greatly appreciated.

Simon Corner