Remove the tops of the strawberries.
Using a small sharp knife, cut out a cone shape inside the middle of each strawberry - you want a small hole in the middle.
Mix together the quark, cream cheese, sweetener and vanilla extract and beat until smooth.
Fill a small freezer bag with the cream cheese mixture. Make sure you get all the mixture in one corner.
Seal the bag and cut the corner. The hole should be quite small so you can pipe inside the strawberries.
Squeeze the filling into each strawberry and sprinkle with digestive crumbs.
Keep them in the fridge until ready to serve.