Public speaking is scary, but you can train yourself to get used to it.
One of the best decisions in my life was to take a drama class in college. The first exercises they made me do ridiculous stuff on stage, repeating non-sense aloud and jumping around like an epileptic kagaroo.
That was a great exercise to shake off the stage fright with a great laugh… and knowing that you can’t do worse than that, everything else you do there on stage will be okay, it is all uphill from there.
Next thing the professor told us that nervousness makes us forget about breathing, so to always remember to breathe deeply and slowly.
The next thing is to train diction and to remove filler words (uh and ums), for that it helps to have a mock audience who can listen to you.
We use these fillers to verbalize the act of thinking, like the blinking LED of a hard drive.
Also you can minimize the act of thinking itself by practicing your speech a lot, so you don’t have to improvise an answer by reasoning (an um hotspot!), but extracting it straight from memory.
If you must think or it is hard to recall, the best move there is to simply pause, don’t be afraid of the silence.