Vanilla Oreo cupcakes : 

1. Preheat the oven to 350°F / 180°C and prepare a cupcake or muffin tin with baking paper.
2. In a bowl, mix and sift together the dry ingredients, flour, baking powder and salt, then set aside.
3. In a large bowl or the bowl of your stand mixer fitted with the whisk attachment, beat the softened butter with the sugar for 2 minutes until creamy and smooth.
4. Add the eggs and vanilla extract, beating again for 2-3 minutes until the mixture is voluminous.
5. Using a spatula, alternately stir in the buttermilk and dry ingredients in batches until smooth.
6. Pour the cupcake batter into the paper cases in the prepared muffin tin, filling them only 3/4 full to avoid overflowing during baking.
7. Bake for around 15 minutes until golden brown and cooked through in the center (plunge a toothpick into the center of the cupcake to check that it's cooked through).
8. Leave the cupcakes to cool slightly in the tin before removing them from the pan and cooling them completely on a wire rack.

Oreo frosting :

1. Place all ingredients in a large bowl: cold mascarpone, whole cream, powdered sugar, vanilla extract and oreo cookie powder.
2. Mix with an electric mixer at medium speed for about 3 minutes until smooth and firm.
3. Line a large piping bag with a star tip and decorate the top of the oreo cupcakes. Place the frosted cupcakes in the fridge for at least 20 minutes before serving.