If only this puzzle had come out a few weeks ago, maybe my sister would have been reminded to take in the basil from her garden and process it as instructed here, instead of leaving it to blacken in the first frost! But I suppose the first frost is later in NYC. Maybe the Boston Globe ran a similar puzzle a month ago. (unlikely)
In general, I am not a huge fan of this type of theme, which is similar to the "long quote" theme, because it is so completely opaque at first, and then, at least in this case, or in the case of a quote that you recognize, can be filled in all at once. And here, there is quite a bit of theme material, so it felt at first like I'd be at this one for a good long while, and then all of a sudden it was done.
My favorite horizontal row was LANCE (49A: Tilter's weapon) and OBVIATES (50A: Renders unnecessary). Both good, interesting words. Thought 1D: Gem of a girl? (OPAL) was a nice clue. Didn't realize that THIRTY was the 4D: Minimum age for a U.S. Senator. For president it's 35, right? I don't know if they ought to perpetuate the misspelling of "biceps" with 6D: Muscle strengthened by curls, informally (BICEP). Maybe our doctor-commenter will chime in with his thoughts on that? And also on the difference between the EKG (8D: Heart test letters) and an "ECG," which is also seen with some frequency.
I didn't think I was familiar with the ALCAN 12D: ____ Highway (historic route to Delta Junction), but after looking it up, I see that I know it better as the Alaska Highway. Further, it starts in a place called "Dawson Creek!"
Overall, I like this puzzle more and more as I write it up. I don't even have time to mention ARNIES (5D: ____ Army (golf fans of old)), LAHR (26D: Cowardly Lion portrayer), or ASCOTS (41D: Items at a haberdashery), the last of which is notable for the fact that it reminds one of the end of "This is Spinal Tap." At least it does this one.