Another tough one and one that has a very tempting "what if" instead of pure logic.
There are two more Xs that can be added to your grid from clues 5 and 11.
Clue 5: mac and cheese cannot be 350 degrees.
Clue 11: 6 people cannot be 400 degrees.
Adding those two Xs doesn't seem to help much.
With that little empty rectangle in the AB category box (upper left), clue 12 unresolved, and clue 5 linking mac and cheese to the AC category box, I go for the "what if" method by choosing one of the clue 12 alternatives.
If 35 minutes = 4 people, then mac = 40 minutes, yams = 35 minutes = 325 degrees = 4. This forces baked ham = 350 degrees = 45 minutes.
Since 4 people now is 35 minutes, clue 11 dictates that 400 degrees can no longer be 40 minutes. With 350 degrees = 45 minutes, 400 degrees can only be 50 minutes.
Clue 11 then puts 6 people = 45 minutes. That's the same row as 350 degrees, and that's a problem.
In the grid, there is an X at 350 and 6. So that "what if" doesn't work.
We choose the other alternative for clue 12, and the solution is obtained.
I think the solution is:
30 minutes  bean  375  8
35 minutes  mac  325  2
40 minutes  yams  350  4
45 minutes  ham  425  6
50 minutes  potatoes  400  5
There must be a pure logic solution for this, but the "what if" in this case was just too tempting.
