French Turbulence: Blood orange macarons

I am a sucker for blood oranges. They are so pretty. And since my lemon macarons tasted so darn good, I had the idea of experimenting with another citrus fruit.
Additionally, I chopped one of my fingers with my ultra-sharp Wusthof knife this week, so maybe all this blood inspired me!
As for my lemon macarons, I used Tartelette's proportions for each key ingredients, and used a cream cheese-based filling.

Blood Orange Macarons: (Macarons a l'Orange Sanguine)

90g egg whites (aged on your kitchen counter for at least 24 hours, uncovered)
30g granulated sugar
110g ground almonds (as finely ground as possible)
200g powdered sugar
zest of one blood orange
Orange and red food coloring

(for the filling:)
4oz cream cheese
1 tbsp butter
Juice of one blood orange
1/4 cup powdered sugar
Orange zest or powder (optional)

In a large bowl, sift together almond powder and powdered sugar, making sure there is no big lumps/crumbs left. Stir in the orange zest.
In a different bowl and using an electric mixer, beat the egg whites at high speed and when they begin to foam, throw in the granulated sugar. Add in a few drops of orange coloring (preferably in powder or gel form). Continue to beat on high until stiff peaks form. You should be able to invert the bowl and the egg whites stick to it without falling.
With a spatula, drop the beaten egg white mixture to the dry ingredients and fold them in gently. For this part, Tartelette says: "Move your spatula from the bottom of the bowl to the edges with one hand, using your other hand to rotate the bowl. Now slap the sides of the bowl until the batter falls in a wide ribbon when you raise your spatula. When you can’t see any crumbs of almond flour and the mixture is shiny and flowing, you are ready to start piping. "
Folding the whites into the almond mixture is really a trick you get with practice. If you fold too long and hard, the macarons you pipe down will be too runny and ressemble crepes (with no feet) after baking. If you don't stir enough, the mixture will be too compact and, when piped down, will not spread nicely but look like, pardon my French, dog piles... So this is where it really gets tricky. (Good luck!)
Right before the last spatula stir, add in a few drops or sprinkles of red coloring (to imitate "blood stain"). Be careful not to over-stir!
Fill up a pastry bag (I use a 40 cm long Wilton bag) with the batter. Cut up the tip of the bag (at about one inch). You can also fit your bag with an Ateco #8 tip.
The macarons can now be piped down on parchment paper or a silpat mat, forming 1 1/2 to 2 1/2-inch circles. Leave about one inch between each macaron.
The macarons should then rest, untouched, for 20 to 30 minutes. This will help create a "crust", and later on, "feet" will appear during baking.
5 minutes before baking macarons, pre-heat your oven at 300F.
The macarons should bake 17 to 18 minutes on the middle rack or slightly over this level (which is what works best for me). This time can be adjusted once you learn what works best with your oven. Simply keep an eye on the macarons so they don't turn brown (they should start browning slightly at the feet and that's when you know they are done.
Let them cool completely!

The cream cheese and butter should be softened, at room temperature. Work them together with a fork or a mixer. Once they are well married, add in the powdered sugar. The orange juice should be incorporated little by little. Don't add too much or the cream cheese mixture will be too runny. You may add in orange zest or powder to boost the orange flavor.

Using a pastry bag or a very small spatula, spread the filling on the flat side of a macaron shell and top with another shell. Repeat with the rest of the shells.

Refrigerate these macarons to let the filling harden and try not to eat any before the next day (or better yet, 2 days!) to let all flavors marry.