I had the same idea about grinding the pecans into powder. Toast them, and then into the FP. As far as your recipe is concerned though, I can't decide on what you might want to do. It will absorb more liquid than normal, but will not behave the same as flour, like someone mentioned, because the nuts will release oil when they cook.
Doing something like a creme brulee might be a good way to go. When made right, there aren't many thing softer than a custard. Another one might be to make a mousse, in which case the suggestion about infusing cream with pecan flavor would probably be the best way to go, although you'd need a lot of pecans to a relatively small amount of cream to get enough flavor for that pecan pie taste.
Another option might be to try pecan oil if you can find it.