Preheat your oven to 350°F (175°C) and line a cupcake pan with liners.
In a large bowl, mix the red velvet cake mix, eggs, melted butter, milk, vanilla, and sour cream (or yogurt).
Blend strawberries until smooth, then stir into the batter.
Mix everything until smooth and well combined don’t overmix.
Fill each cupcake liner about 2/3 full with batter.
Bake for 20–22 minutes or until a toothpick comes out clean.
While they cool, beat together butter, cream cheese, vanilla, and powdered sugar to make the frosting.
Once cooled, frost the cupcakes and garnish with fresh strawberry slices (optional).