Preheat the oven to 180°C.
Put the raspberries an ovenproof dish. Scatter half of the sugar on top, then drizzle with the vanilla extract.
In a bowl, rub the butter with the flour until you get a mixture resembling breadcrumbs. Add the remaining sugar, ground almond and oats. Mix gently. You can add a pinch or two cinnamon too, if liked.
Cover the raspberries evenly with the crumble, slightly pressing down, then scatter some almond flakes on the top.
Bake for about 20 minutes until golden.
Serve warm.