Sure you can do this, you can also mash a high gravity wort and dilute w/ water to proper gavity, but your efficiency will suffer a bit, as will hop utilization. Another option is called the Texas two step, make a 1/2 batch and pitch the yeast, the following day make another half batch and add it to the first 1/2 batch...
Or if you have a second pot, you can split the boil in two pots.
Or if your mash tun is big enough, you could do a full volume mash, drain off half and boil, then drain off the second half and boil...many ways to accomplish your goal.