Line 2 baking sheets with non-stick baking mats and set aside. 

Process the almond four and powdered sugar in a food processor for about 1 minute then sift into a bowl, set aside.

In the bowl of a freshly cleaned and dried stand mixer, whisk together the egg whites and granulated sugar. Place the mixing bowl over a pot of simmering water and heat, whisking constantly, until the sugar is melted and the mixture is warm to the touch.

Return the bowl to your stand mixer, fitted with the whisk attachment. Turn the mixer to high and whisk the egg mixture until it forms stiff peaks and the bowl is no longer hot. 

Add in the vanilla and food coloring and whip for another minute.

Sift the dry ingredients into the mixing bowl on top of the egg whites.

Take a spatula and scrape down any unincorporated meringue from the sides of the bowl. Run the spatula around the bottom once to get any bits that didn't get mixed in. Smush the batter along the sides of the bowl, then gather together. Lift the batter and let it drizzle from your spatula back into the bowl. If it moves like lava, it is ready.

Scoop the batter into a pastry bag fitted with a wide round tip. Pipe evenly sized rounds onto the prepared baking sheets.

Bang the baking sheets on the counter several times to release any air bubbles. Let the macarons sit out until the tops are dry and a skin has formed. about 30 - 60 minutes.

Preheat the oven to 290°F. Bake the macarons one sheet at a time for about 25 - 26 minutes, or until you can lift the cover of a macaron from the baking sheet easily.

Remove from the oven and allow to cool completely.

Make the frosting while the macarons are baking. Beat the butter until smooth, then add in the powdered sugar. Add in the heavy cream and vanilla then beat until smooth. Fill a piping bag with a round tip with the frosting.

Before you remove the shells, add the blood splatter. Mix together the food coloring and the vodka. Dip in a new small paint brush and tap the brush against your finger to splatter the coloring over the shells. Move the brush around quickly as you splatter so there are not any very large drops that will soak through the shell.

Allow the splatter to dry - you can speed up the process by leaving them by a fan

Pipe half of the shells with a round of frosting, and add a teaspoon to the middle f the round. Sandwich with the remaining shells.