jonsblond’s idea is good, especially if you’re already a couple.
I would like to remind you of a general rule about the cooking if this is a date: there is a possibility that she’ll stand you up, and you don’t want to spend the whole day in the kitchen (and also stink when she gets there) and end up eating something cold. There are two ways of getting around this issue:
1) make something in the morning that you could warm up later. I usually go for beef goulash, which is quite easy. I broil the meat in medium-sized cubes and then throw in some onions and salt. Then some wine, tomato sauce with some water (half-fill the pot), ground garlic, some red pepper, muskat, a stick of cinnamon and a couple of myrtle leaves. Bring the whole thing to boil and then let it simmer for a couple of hours. You can either put in some whole potatoes for the last hour or make some puree just before she gets there (it is also easy to do and doesn’t stink). And just warm up the pot when she arrives.
2) an on-the-spot meal that she can watch you prepare. This can be quite impressive if you are confident enough to make it flambee, but let’s stick to the normal recipe for now:
you buy a couple of chicken breasts and cut them into small cubes (or stripes). Also some peppers (try different coloured ones). And an onion. Have the things ready (might want to use gloves when cutting the onion) and then when she gets there, throw everything into a pan (I prefer to use a wok). Get some olive oil really hot and start with the chicken, remembering to turn it over so it doesn’t get burnt. You only need a couple of minutes, then throw in the other ingredients, some salt (and maybe tabasco) and perhaps a drop of wine (if you didn’t use it all on the other recipe). You could serve the whole thing with rice that you have already prepared while waiting for her to show up, or some other side dish of your choice (I’ve always had a problem with this bit because I want to avoid frying chips the last moment). Would be nice to have some fresh bread ready.
Serve both meals with a nice glass of wine (find out what she likes). Candles, nice music, a nice smell to the place (which you will have of course cleaned the previous day) are all vital details. And of course the way you look.
Do not slave all day in the kitchen and end up looking (and smelling) like a cook. Try one of the recipes above and you can open the door in your best suit (and even fry the chicken in it).