What I'm looking for is a 1500 calorie per day diet that is painfully simple
to follow. If I could just eat the exact same, easy-to-prepare meal every
day, I could follow it.

If you're really willing to eat the same thing every day, then what's
the problem?

Read some labels, add up the calories, stock up.

Turkey sandwich on WW bun. Healthy Choice soups and frozen dinners.
WW pasta with real sauce (not the high fructose corn syrup crap).
Grilled chicken breast and salad.

And the list goes on and on.

I think most of us managed to do this without paying a doctor or
nutritionist. The info is freely available.

Of course, "I can't afford a nutritionist" is always a great excuse
for delaying a lifestyle change.