I mean directly after the Normans arived - nothing by anyone in the last century, for example. I know of the Peterbourough Cronicle for example and that the not so gradual evolution into middle English complicates the question, nevertheless... curiosity.
This is difficult to answer, the last administrative document extant in Old English in from 1070. However, do you mean original text or just text, because Old English texts were being copied in Old English well into the thirteenth century - for example, the Hexateuch - when it is arguable that Old English as a language had developed into a different one. But, to get to the point, here is an article that directly answers your question. I'd also look at Mary Swan and Elaine Trehaine's Rewriting Old English in the Twelfth Century.