Line two cupcake pans with cupcake liners and preheat the oven to 350 degrees.

In a medium sized bowl, beat butter on medium speed with an electric mixer until smooth and creamy. Add cookie butter and mix until incorporated. Add sugar and vanilla; mix well. Add eggs one at a time, mixing well after each.

In another bowl, combine flour, baking powder, and salt. Add half of the flour mixture and half of the buttermilk to the sugar mixture. Mix until just combined. Repeat with the second half of the flour and buttermilk and mix well.

Fill cupcake liners about 2/3 full of batter. Bake for 20 minutes or until lightly golden brown on top. Let the cupcakes cool completely before frosting.

In the bowl of a stand mixer, cream butter on medium speed until smooth and creamy. Add vanilla, and milk. Mix well.

Add half of the powdered sugar, mix on low speed until just combined, and then medium speed until completely combined. Repeat with the second half of the powdered sugar. Set vanilla frosting aside.

In the bowl of a stand mixer, cream butter on medium speed until smooth and creamy. Add cookie butter and milk. Mix well. Add half of the powdered sugar, mix on low speed until just combined, and then medium speed until completely combined. Repeat with the second half of the powdered sugar.

To make the two-toned frosting, you'll need a large cup and a piping bag fitted with a large star tip (or the OXO decorating bottle kit!). Place the piping bag in the cup and fold the bag over the cup. Using a rubber spatula, scoop up some vanilla frosting and add it to the piping bag by scraping it off of the spatula with the edge of the cup. Repeat on the other side of the cup with the cookie butter frosting. Continue adding one scoop of vanilla and one scoop of cookie butter until the bag is full. Then pipe swirls of frosting onto the cooled cupcakes and garnish with a cookie butter sandwich cookie!