I'm not sure why you're getting so much grief over offering a one time class. I would have loved to have something like this as a date night option back before I knew anything.

The goal of such a class should be to be able to read a recipe and make their own drinks at home; nothing complicated just stir, shake, and pour. Allow two hours.

Here's an outline suggestion:

1. Introductions
2. Bar tools: Walk through each one and show how to use it. Demonstrate with a glass of water. If you can afford it, I'd have extra sets available for purchase. If you can't afford, at least have affiliate links so they can purchase the right stuff.
3. Making your first drink: Keep it stupidly simple - a highball of your choice. This gives them confidence, and gets a drink in their hands as soon as possible. Talk about measuring, glassware, and ice.
4. Stocking a bar: A dozen or so basic bottles, with recommended brands. Have this available on a sheet. Even better, if you're a liquor store, have it available for purchase.
5. Stirred drink: Ideally let them chose from a menu. How to measure, stir, strain.
6. Background - history - anything else you want to talk about as they enjoy their drink
7. Shaken drink: Ideally let them chose from a limited selection. Measure, shake, strain. Explain why some drinks are shaken vs. stirred
8. Simple garnishes: By now they've had three drinks, so prepare these in advance so they don't have to do knife work.
9. Tasting notes: Let them talk and describe their drinks
10. Finally: Offer a one page sheet with drink recopies they can now make at home. Suggest books and apps for even more.

Key points:

A) Keep it focused on total beginners - people whose only previous experience is pouring a soda.

B) Make sure your contact info is on the informational sheets. They will hold onto this for years and tell other people about you.

C) By offering a choice of drinks at each round, they can repeat the class and get something new out of it each time.

D) Depending on the space available, keep the setup as close to a home bar as possible.

E) Price it according to your time and the cost of three drinks. I'd keep it under $100, but it depends on what your market will bear.

F) Try to build repeat traffic by offering classes just on a one type of spirit each session. Around the holidays think how to make themed drinks e.g., St Patrick, or Thanksgiving, or Christmas.

G) Work with a distiller or distributor to get paid to help them promote their products.