In a large mixing bowl, mix the 1 stick unsalted butter, 3/4 cup creamy peanut butter, and 1 1/3 sugar for about 2 minutes. Then slowly add in the 1 egg 2 tablespoons milk 2 teaspoons pure vanilla extract and 1 teaspoon food coloring mix again for another 2 minutes, until light and fluffy.
In another mixing bowl, mix the 3 tablespoons unsweetened cocoa 1 1/2 cup all-purpose flour, 1 teaspoon baking soda and 1/2 teaspoon salt.
Add the two mixtures together and mix well. Mix until fluffy.
Add a piece of parchment paper to the basket. In a small bowl, add your sanding sugar, roll the dough into 2-inch pieces, and coat the balls with the 1/2 cup red sanding sugar set the air fryer temperature to 320 degrees F, air fryer setting for 5-6 minutes.
When the cookies are done, wait about 10 minutes, and then put a 1/2 cup red sanding sugar in the cookie's center.