Beat 1 cup butter and 2 oz cream cheese on medium for 2 minutes, add 1 1/2 cups granulated sugar and beat 2 more minutes, then mix in the egg, egg yolk, and 2 tsp vanilla extract until just combined.

Stir in the 1 1/2 tsp pink gel food coloring, then whisk together the flour, baking soda, 1/2 tsp salt, and cream of tartar in a separate bowl and mix into the wet ingredients in 2 additions on low speed until no dry streaks remain.

Cover the dough and refrigerate for 45 minutes, then portion into 12 balls of about 75g each, place on a parchment-lined baking sheet 3 inches apart, and flatten each to about 1/2 inch thick.

Bake at 375°F (190°C) for 11 to 13 minutes until edges are set and tops are matte, cool on the pan for 5 minutes, then transfer to a wire rack and cool completely for about 30 minutes.

Beat 8 oz cream cheese and 1/4 cup butter for 2 minutes, add 3 cups sifted powdered sugar in 2 additions, then mix in 1 1/2 tsp vanilla extract and a pinch of salt and beat on medium for 1 minute until the frosting holds a soft peak.

Swirl 3 to 4 tbsp of frosting onto each cooled cookie with the back of a spoon, dust with pink sanding sugar, and serve at room temperature.