Is “homeopathic” an acceptable unit of measure?
Vegemite is now recognised as having umami taste [one of the big five tastes - often called savoury or browny/roasty flavour] although as someone who doesn’t normally add additional salt to food I find its saltiness sometimes dominates.
Muffins don’t have a holey side. You may be thinking of a crumpet. Muffins are the ones that split in the middle.
You know what’s nice? Big dob of butter, little scraping of honey, tiny scraping of Vegemite. Mmmmm…
The magic of the internet.
It is lunch time here. I have Vegemite and an English muffin. My Vegemite is in a tube, but that doesn’t matter…
later…
Turns out about a teaspoon per half. And it was the same for the half that I then melted cheese on.
When you split the muffin in half, the cut side is the holey side. Therefore, one English muffin, split in the middle, yields two holey sides, or if you prefer, two smooth outsides and two holey insides.
I know what crumpets are-- smooth on one side, holey on the other, yummy all over.
Quoting Barack Obama, I see. 
He’s wrong.
Maybe, but more for me.
Let me also decry the ongoing debate about which yeast spread is best.
I love them all, each for different things. I can no more pick my ‘favorite’ yeast extract than I’d pick my favorite child. Marmite, Vegemite, Cenovis, Aussie Mite, Mighty Mite, NZ Marmite, they all have redeeming characteristics and endearing quirks.
My usual dollop measures as 1/2 teaspoon. I’ve no real preference between Marmite and Vegemite, but consistently find Marmite selling for much less.
Typically Marmite can be had on Amazon for under $13 per 500 gms. Vegemite is closer to $20.
Mine costs more like $120. (In the 2.5 kg pail.)
But they give you a free paint roller, so that’s good.
Of course the only reason to measure Vegemite by the spoonful is if you are going to eat it by the spoonful.
Otherwise Vegemite is measured in knife blade smears, which is a technical term.
By the same technical basis it is a fact that there is always enough Vegemite left in an empty jar to spread on one last piece of buttered toast.
This may be because you didn’t grow up with one or the other as a household staple. I grew up with Marmite and didn’t taste Vegemite until I was about 20. Consequently, vegemite will always be the pale imitation (literally - Marmite is darker and stronger).
For Marmite, I would spread a very thin layer on muffins (with lots of butter), so doubt it’s a teaspoon’s worth. Vegemite, I wouldn’t touch. I find it a bit gritty in comparison with the silky smooth of Great British Marmite TM.
Have done. 
But what is the volume of a knife blade smear? I had to find out.
Had to check - about half a teaspoon [took my usual knifeload and scraped it with a spoon measure to find out the amount.]
I do drop about a tablespoon per 2 quart when I make beef stew or a couple teaspoons for 2 quarts beef based soups, gives it that ‘hydrolized yeast’ flavor that is missing from commercial product.
And now, the problem is that, in her recovery, Mrs. L.A. has finished off the English muffins!
Oh, wait. I need to hit the store on my way home. All is good.