Welcome Charlie,
ANY coil that works on the first try IS a success!
Here are a few simple suggestions that might improve your results:
1) The pizza pan/ cookie tin combo is a problem. The thin edge of
the pan, and the sharp edges of the tin allow charge to bleed off,
reducing peak voltage. The fatter and more rounded edge of a toroid
allows more charge build-up. A piece of aluminum dryer duct or
foil-covered Styrofoam doughnut will serve you much better.
2) Your spark-gap definitely has heating problems. If you are not yet
going to use a multi-gap, then at least do the following: (a) Use
heavier, brass, round-headed bolts or threaded rods with brass balls.
Brass conducts heat and electricity better than steel, and larger
terminals mean better heat dissipation. Rounded terminals mean less
corona loss. (b) Put a fan or other blower on the gap. Hot, ionized
air in and around the gap causes it to fire sooner preventing full
charge build-up. (c) Slightly reduce your gap width. 5-6 mm (1/5 to
1/4 in.) will prevent a misfire from overvolting your transformer and
your caps.