Instructions

1. Line two sheet pans with parchment paper. I used a 1½-inch round cookie cutter to draw circles on the parchment paper and flip over the paper (drawing side down). Prepare a pastry bag with a round tip. I used Wilton 2A.
2. Using a food processor, pulse the powdered sugar, walnut pieces, almond flour and zest into fine powder. Sift several times until there is less than 2 tablespoons of almond bits left. Add these to the mixture.
3. In the bowl of an electric mixer with the whisk attachment, combine the egg whites, cream of tartar, sugar and salt. Whip on medium-high speed until stiff peaks form, about 5-7 minutes. Add the food coloring and whip for another minute.
4. Add the dry ingredients to the meringue and fold with a rubber spatula. Gently fold to deflate the meringue by pressing against the side of bowl and scooping from bottom until batter is smooth and shiny; about 20-25 folds. To check consistency, drop a spoonful of batter and it should have a peak that quickly relaxes back into the batter. Start checking the batter after 20 folds.
5. Transfer batter into pastry bag and pipe the batter into the pre-traced circles on the baking sheet. Tap baking sheet hard on counter to release any air bubbles trapped in the batter. Let shells sit on counter for 20-30 minutes to dry.
6. Preheat oven to 375 degrees F. When ready to bake, put macarons in heated oven and reduce temperature immediately to 325 degrees. Bake for 11-12 minutes. Remove from oven and transfer shells to a cooling rack. Remember to raise the temperature back up to 375 degrees F before baking the next batch.

1. Whip the butter until light and creamy. Add in the rest of the ingredients and mix on low until combined. Increase speed to low and whip for additional 2-3 minutes.
2. Fill macarons with blood orange filling. Store in refrigerator until ready to serve. Let get to room temperature before enjoying!