To make strawberry filling (to emulate blood), in a small saucepan, combine the strawberries, sugar, water, and cornstarch. Bring to a slow simmer and stir fairly consistently for 4-5 minutes or until the mixture begins to thicken. Once it has thickened to a jelly-like consistency, remove from heat and let cool.

Once completely cool, spread filling on top of cooled brownies. Leave about 1/4 of a cup reserved to fill in the slash-marks in the buttercream. Place in the refrigerator for at least an hour to set.

While cooling, prepare the buttercream. Beat all the buttercream ingredients together until smooth.

Once the strawberry filling has set, top with buttercream, and place in the refrigerator for another hour or so.

To decorate, cut brownies into squares. Using some sort of prongs (I used a serving spoon with prongs) "slash" through the buttercream on each brownie. To get more of a "bloody" effect, carefully fill in the slash-marks with the reserved strawberry filling.