Preheat your oven to 350°F (180°C). Line a baking sheet with parchment paper and set aside.
In a medium-sized bowl, using an electric hand mixer or the paddle attachment on a stand mixer, cream together the softened butter and granulated sugar until light and fluffy, about 3 minutes.
½ cup unsalted butter, 1¼ cups granulated sugar
Scrape down the sides and bottom of the bowl with a rubber spatula. Add the whole egg and mix on medium speed until well combined, about 30 seconds. Add the egg yolk and mix for an additional 15 seconds.
1 large egg, 1 large egg yolk
Mix in the red velvet emulsion (or red gel food coloring) and vanilla on low speed until just combined.
2 teaspoons LorAnn's Red Velvet Emulsion, 1 teaspoon pure vanilla extract
Add the cocoa powder, flour, salt, cornstarch, and baking powder to the wet ingredients. Mix on low speed until just combined, being careful not to overmix. Scrape down the sides and bottom of the bowl as needed.
Using a 4-tablespoon cookie scoop or weighing out 3.5 ounces of dough per cookie, scoop the dough onto the prepared baking sheets, leaving space between each cookie. You should have about 9 cookies.
Bake in the preheated oven for 10 minutes or until the edges are set and the centers are slightly soft.
Allow the cookies to cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.
For the Cream Cheese Frosting:
In a medium-sized bowl, using an electric hand mixer, beat the softened butter and cream cheese on medium speed for 2 minutes. Scrape down the sides and bottom of the bowl, then beat for another 2 minutes.
4 ounces cream cheese, ½ cup unsalted butter, 1 tablespoon heavy whipping cream, ¼ teaspoon vanilla extract, 2 cups powdered sugar, Pinch of salt
With the mixer on low speed, gradually add the powdered sugar. Then mix in the vanilla, heavy whipping cream, and a pinch of salt.
Once combined, increase the speed to medium-high and beat for 2-3 minutes until the frosting is smooth and fluffy.
Assembly:
Once the cookies are completely cooled, spread or pipe the cream cheese frosting onto each cookie using a piping bag or an offset spatula.