Preheat oven to 350 degrees.
Put topping ingredients into a bowl and quickly mix to incorporate the butter. Sprinkle onto a baking sheet and bake until golden and crispy.
Put frozen berries into the bowl of a food processor and pulse until they start to break down. Add yogurt, corn syrup and vanilla and continue to process. Pulse until incorporated and smooth. It will frozen enough to serve at this point. Scoop and serve or store in airtight container in the freezer.
Top with crumble.