Red Velvet Sandwich Cookies

i took a box of Duncan Hinds® Velvet Cake Mix and incorporated Martha Stewart® Vanilla Butter cream Filling to make the cookies.  i did not use Duncan Hines® Creamy Home-Style Classic Vanilla Frosting.

for the cookies:

• 1 box Duncan Hines® Red Velvet Cake Mix
• 1 large egg
• 1 teaspoon vanilla extract
• 1/2 cup butter

1. Melt butter; set aside to cool. Place cake mix, egg, cooled butter and vanilla in large mixing bowl. Mix by hand until well blended and dough is formed.

2. Form dough into a smooth 12-inch log on wax paper or parchment making sure it is even in thickness end to end. Wrap in wax paper; seal in plastic wrap. Refrigerate 1 hour or overnight.

3. Preheat oven to 350°F. Lightly grease baking sheets. Unwrap dough log and set on wax paper. Using a sharp knife, cut into 48 slices about 1/4- inch thick. Place on cool baking sheets about 2 inches apart.

4. Bake, 1 sheet at a time, in center of oven for 10 to 12 minutes or until set. Cool 1 minute. Transfer to wire rack to cool completely.

5. Spread frosting on half the cookies. Top each frosted cookie with another cookie. Gently press together.

 for the butter cream:

1/2 cup (1 stick) unsalted butter, softened
1 cup confectioners' sugar
1/2 teaspoon pure vanilla extract

Beat butter with an electric mixer on medium-high speed until creamy, about 2 minutes. Reduce speed to medium, and beat in confectioners' sugar, 1/2 cup at a time, scraping down side of bowl as necessary, until pale and fluffy, about 5 minutes. Add vanilla, and beat until smooth.