Place the strawberries in a shallow dish and sprinkle the caster sugar on top. Stir to combine. Let sit for at least 30 minutes.
Meanwhile, add the pretzels to a food processor. Pulse until they are broken into small chunks. Some will pulverize, some will stay chunky - That’s all good!
Drizzle the melted butter and cinnamon over the crushed pretzels and pulse a few times to combine. Scrape mixture out of food processor and set aside.
In a small bowl, add the yogurt and brown sugar. Whisk together to break up any brown sugar lumps.
Into each serving vessel, layer yogurt, strawberries, and pretzel mixture. Repeat. Garnish with extra yogurt and crushed pretzels.