split turkey breast

My guess is about an hour, maybe a little longer. To be safe, always go by temperature. If you want both breasts to come out at the same time, give the larger one a little head start. And keep your eye on them, cover with foil if they brown too much.

ok i have to ask one one question...i have 2 pieces one is about 2.3 and one about 3.25 i get the 400degrees but can you give me a ballpark how long to cook ...i know i can start with the 3.25 and then add the 2.3

Actually there's not much difference between a breast and a whole turkey except the amount of cooking time. And, as with a whole bird, you can do it simply or as fancy as you please.

For a simple roast, it's best to get it up off the pan so air can get underneath and so it won't stew. Use a rack if you have one or make some risers out of crumpled aluminum foil. Spread some neutral oil or clarified butter over the skin, throw on a little salt and roast bone side down. Pull it at 160F and let it rest for 15 or 20 minutes before carving.

I'd start by brining the breast (this recipe includes a delicious brine that will add great flavor and keep the breast meat juicy: http://food52.com/recipes/19368_michael_ruhlmans_rosemarybrined_buttermilk_fried_chicken). Then, I'd roast the breast, skin-side up, at about 400 degrees, basting with butter or olive oil a couple of times as it cooks. Or, you could drape a few strips of bacon across the top of the breast to keep the meat from drying out as it cooks.

Yes - bone down, breast side up. It will cook faster than the whole turkey so watch your timing.