As all busy balabustas know well, food can be divided into two categories: the "real" food and the "luxuries." In the first category are bread, soup, fish, meat, vegetables, etc.; in the second category are desserts, cakes, nice side dishes, fancy "extras" like
knaidlach, homemade foods that we can do without or buy ready-made, etc.
A wise friend of mine once said, "Nothing is hard to make; but everything takes time!" The more pressured you are, the less time you have for the second category. However with advance planning and wise use of your trusty freezer you can include some category II foods in your menu also. [By no means am I trying to instill guilt in the hearts of those who serve no-frills, basic menus. I am merely suggesting ways to "fancy up" your meals for special occasions (Shabbos, Yom Tov, Sheva Brochos, special company, etc.) without going crazy.]
Most dishes based upon flour or dough freeze beautifully, and hence can be prepared months in advance in a deep freezer. I have successfully frozen knaidlach, knishes, pancake batter, borekas, blintzes, kishka (cholent kugel) and kreplach. (All of these are baked, fried, or cooked erev Yom Tov or Shabbos). Even though the "Spice and Spirit Lubavitch Cookbook" knaidlach recipe takes me only 8 minutes to prepare (I timed it!), it does make a few utensils dirty, and you do have to spend time shaping the balls. It makes sense to prepare a multiple of the recipe during the summer, for example, and then during Tishrei every Erev Shabbos and Yom Tov while you're heating your soup, you can blithely throw in as many knaidlach as necessary and watch your guests say -- "Wow -- homemade knaidlach! -- you had time for this too?" (You must let the soup simmer for a half hour before candle lighting to cook and expand the knaidlach).
My sister and I both find making kreplach a "patchkerai," but since it's traditional for Erev Yom Kippur, Hosha'ana Rabba and Purim, we have often made a large batch before Yom Kippur, divided it into three sections and, you guessed it, served the third batch on Purim. It does say in seforim that there's a strong connection between Purim and Yom HakiPurim. We're just bringing it down to this world, lematah mi-asarah tefachim. It is nice in the hectic weeks before Purim when you're busy with preparing your mishloach monos, seudas, Purim costumes (and thinking about the next Yom Tov that comes exactly one month after Purim), that there's one messy chore you can eliminate.
The same principle applies to side dishes, especially cooked ones. Here it really makes sense to prepare in large quantities and freeze -- since side dishes are generally served in smaller amounts and you don't want to go to a lot of trouble to produce one bowl of something. In my experience the following freeze beautifully: tzimmes, techina, Kabetchke (eggplant side dish -- delicious), beet side dishes. As a matter of fact, if you'd like to experiment with your favorites, all you have to do is freeze a small amount next time you prepare that recipe. You be the judge of whether it freezes well or not!
Candles can also be frozen for a few hours before using -- even though they're not served (they simply drip much less if they've been frozen Erev Shabbos. Don't ask me why -- I picked this one up in a goyishe household hints book). Not all kugels freeze equally well. Lukshen kugels freeze better than potato kugels, in my experience. Kugels can get watery when defrosted but I discovered a trick along the way. If you are preparing a few kugels ahead of time -- fry them on one side only. Freeze them that way. On the day you need to serve the kugel, put it on a plate and defrost. Heat a heavy skillet with oil till very hot, carefully slip the kugel into the pan, cook on low flame till done, cool in pan so it won't stick. As it's cooking, the extra moisture and "freezer taste" will actually vanish. Let me know if anyone discovered that this kugel wasn't made from scratch Erev Shabbos. For those who usually bake their kugels in the oven, I suggest preparing the kugel completely, and putting it on baking paper and freezing raw. On Erev Shabbos or Yom Tov, defrost and bake as usual.
Note: As for freezing individual portions: I generally do not freeze soup in individual portions since it takes up a lot of space in the freezer. I do freeze my soup in different size plastic containers. If a guest comes unexpectedly or I run out, it is no problem to heat up a small container of frozen soup. Within minutes there is a piping hot portion for that person too.