Preheat your oven to 350°F (175°C). Line your cupcake pan with paper liners.

In a large bowl, whisk together the white cake mix, buttermilk, oil, eggs, and lemon zest. Stir just until smooth—don’t overmix.

Gently fold in the raspberries. I like to toss them in a teaspoon of flour first so they don’t all sink to the bottom.

Divide the batter evenly between the cupcake liners, filling each about 2/3 full. Bake for 18–22 minutes, or until a toothpick comes out clean.

Let the cupcakes cool in the pan for about 5 minutes, then move them to a wire rack to cool completely before frosting.

In a medium bowl, beat the softened butter and cream cheese until smooth. Add in the powdered sugar, lemon juice, lemon zest, and vanilla. Beat until light and fluffy.

Once the cupcakes are completely cool, frost them using a spoon, knife, or piping bag—whatever you’ve got works!