My thought would be to break it down like this: (totally an example of how I would try to figure it out, not based on experience, so take it with a grain of salt…)
1/2 hour of time for the initial contact, scheduling the appointment, getting your studio ready for the shoot.
1 hour time in-studio
1-2 hours in post-production
1/2 hour of follow-up, sending files, billing the client etc.
for a total of 3-4 hours x (20$)/hour before taxes (or whatever you think is reasonable) = 60-80$
plus, add any expenses directly related to the shoot (fresh flowers, 20$) = 80-100$
Finally, add the fixed expenses and equipment expenses. This is the complicated part. Yearly costs include: studio rental space, insurance, telephone, internet, web hosting, advertising, Lenspiration Pro membership, business cards, and some software. Equipment expenses are the cost of your equipment and studio divided by the likely lifespan of the equipment. These would include cameras, computers, software, lighting, backgrounds, lenses, filters, etc. Then you can take a guess how many shoots you could do in a year. (My guess for 1-hour in-studio shoots is 2 per day (remember 1 1-hour shoot takes 4 hours of your time), 45 weeks a year would be the absolute max without hiring an assistant, so 450 one-hour sessions per year.)
If your fixed yearly expenses are 5000$ and your yearly equipment costs are 4000$, then divide that by 450 shoots = 20$ per shoot. So your total would be between 100$ and 120$ for a 1-hour studio session.
Note: Please, don’t just go and charge 100$ just because I said so! Do the math yourself, and figure it out to your own business, and compare it with what others in your area are charging, keeping in mind how their quality (and perks) compares to yours. The same can be done with shooting weddings and any other type of contract-type photography.