You must create an item wich has the name of the recipie.
Then, a trigger:
Conditions: -Unit buy an item
Conditions: -Buying unit has an item of type "component 1 of recipie"
-Buying unit has an item of type "component 2 of recipie"
Event: -Remove item carried by buying unit of type " component 1"
-Remove item carried by buying unit of type " component 2"
-Create "item created by the recipie" at position of buying unit
-Give last created item to buying unit