This is inspired by those bake-it-yourself items I see in shops which are e.g. quite pale baguettes they expect me to throw into the oven for 10 minutes to end up with a "freshly baked" good. I know it's not the same thing as actually freshly baked but it is still vastly better than a few days old chunk of bread sprinkled with water and reheated in the oven. Is there anything specific I need to do to my muffins to do them like that? Would a similar procedure to par-baked breads work (i.e. baking them first at lower temperature and then finishing off later with a higher blast?) I'm curious about any thoughts. BTW Those are going to be whole wheat breakfast muffins with freshly foraged bilberries :) This is also the reason I'm asking - I need to use them right now but I don't expect to have people around to consume them until later in the week... 
There's a big difference between what's possible with bread and with muffins or cakes because bread is from a dough and the rest is a batter. Bread dough has a lot of structure to begin because of the gluten, so you can partially cook it to set that structure and then crisp it up later. You can't do the same with a batter as there's no structure. When you bake a batter the heat turns water to steam, and the leavening agents react, causing air to form. At the same time a crystalline structure forms around the sugar and starch, which traps the expanding gases and the structure expands upwards, i.e. rises because the shape of the pan restricts it to one direction. Once the expansion is complete cooking then completes the crystallization of the structure, making it semi-rigid. If you interrupt that process before it's complete the cake/muffin won't have the strength to hold up its expansion and the whole thing collapses into a dense, undercooked mess. Fortunately for you muffins keep their freshness longer than bread, and also freeze well. Some fruit muffins actually get better with a couple of days in the refrigerator, you may want to try it with yours. 