Using a large mixing bowl, stir together dry ingredients, then add in the wet ones. Stir until dry ingredients are moistened (can use electric mixer on slow).
Using a sturdy electric mixer, beat on medium for 2 minutes. (If you have a wimpy mixer, leave out the carrots from previous step, beat 2 minutes, then fold in carrots by hand, being careful not to destroy too much loft in the batter.)
Pour batter into prepared baking pan and level off, distributing evenly.
Place in oven on center rack and bake at 325°F for 50 - 60 minutes, until a wooden toothpick comes out clean from center.
Cool completely on wire rack. You can leave in the pan or turn out onto a tray. Frost when cool.
CREAM CHEESE FROSTING
While cake is baking or cooling, combine softened cream cheese & butter and beat until fluffy.
Stir salt into powdered sugar.
Add powdered sugar mixture to cream cheese mixture a little at a time, beating until smooth. Stir in vanilla.
Spread frosting evenly over completely cooled cake. If you have turned cake out of pan, you'll need to make frosting layer a little thinner, but there will probably be extra frosting if you leave the cake in the pan.
Sprinkle with nuts if desired and serve it forth!
Due to the high moisture content and cream cheese frosting, this cake needs to be stored, covered, in the refrigerator should you be lucky enough to have leftovers. But it should be fine sitting out on the counter for a few hours.
If you want to make the cake ahead of your event, I'm told it freezes well, but don't frost until ready to serve. (I've never tried to freeze the frosting as it is cheese.) (OK, I've never frozen the cake either, but a friend does regularly. It never lasts long enough at my house to make it to the freezer!)
If you want to try to make this a little more healthy, you can substitute half the all purpose flour with whole wheat flour.
Also, you can substitute honey for the sugar. Some folks sub at a 1 to 1 basis, but I find that 2/3 to 1 works well for me. Additionally, you should probably cut back on some other moisture in the recipe, either the oil or the egg, say half the oil OR one less egg (for a total of 3). Using less egg could affect the consistency of the cake, so play around with the ratios and let me know what you did and how it turned out. Whatever you do, don't try an untested experiment for a big event!