Please Remind Me -- Halachic Question

Hypothetical situation: I have something (say a cake, just for example sake) that requires an hour to bake. Can I stick it into the oven at, say, 45 minutes to shabbat and let it finish its cooking during shabbat? Is there a specific percentage that it has to be cooked before shabbat comes in? Assume timed bake or that leaving the oven on over shabbat is not a problem.

We tend to (a) do cooking Thursday night and just be warming stuff up and (b) be using the hotplate and not the oven, so I haven't contemplated this recently. I seem to recall something about cholent having to be 100% cooked or 100% raw before shabbat, but I'm not at all sure about that.

A Special Shabbat

This week's Shabbat is, while not unique, unusual: on Shabbat morning, we'll read from 3 Torah scrolls:

1. For the weekly parsha (Miketz)

2. For the Chanukah maftir

3. For the Rosh Chodesh (beginning of the new month) maftir

There is always a Rosh Chodesh during Chanukah. There is always at least one Shabbat during Chanukah. When they fall out together like this, it requires a bit of finessing.

Shabbat shalom, chodesh tov, and chag Chanukah sameach!