To achieve this effect, I place the whole loin in the freezer for about 30 minutes, to enable easier cutting and for security of form.
Make a cut horizontally along the length of the loin, stopping about 1/2 inch of the end. This cut is made about 1/3 of the way down from the top of the loin.
Flip the loin over and repeat.
This enables the loin to be opened like a fold-out book of sorts.
Using a rolling pin and/or meat mallet, flatten the loin to make as even as possible all the way across.
Cover the loin with plastic wrap to protect the meat while flattening.
Make a stuffing with more Greens(I used Spinach) than bread crumbs for a delicious union.
Use a measuring cup to evenly distribute the stuffing along the length of the loin.
Carefully and slowly roll the loin lengthwise and finish with the open seam facing down.
Secure the loin in intervals with butcher's twine.
Carefully curl the loin into a pinwheel and secure with a piece of butcher's twine, around the circumference of the loin.
For a fantastic golden glaze on your protein, use an egg wash. This helps browning and also to hold in moisture as the loin roasts! And remember, don't forget to remove all the pieces of twine, after the loin has cooked.