Dip the speculoos in the coffee and crumble on a plate. The coffee is only there to be drunk. Do not dissolve the biscuits in it.
Divide half of the speculoos mixture into 8 tall glasses and press lightly on the bottom. Put a layer of berries on top. Mix the yogurt with the vanilla sugar. Cover the glasses with yogurt. Spread the remaining speculoos mixture on top. Chill for approx. 2 hours.