Preheat & Prep:
Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.

Make the Batter:
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then mix in the vanilla extract.
In a separate bowl, whisk together the flour, baking powder, and salt. Alternately add the dry ingredients and milk to the creamed mixture, beginning and ending with the dry ingredients, until just combined.

Create the Nutella Swirl:
Spoon about half of the cupcake batter into each cupcake liner. Add a small dollop (about 1/2 tsp) of Nutella on top, then cover with the remaining batter. Gently use a toothpick or skewer to swirl the Nutella into the batter.

Bake:
Bake in the preheated oven for 18–20 minutes, or until a toothpick inserted into the center comes out clean. Remove the cupcakes from the oven and let them cool completely on a wire rack.

Prepare the Strawberry Buttercream:
Beat the softened butter until creamy. Gradually add the powdered sugar, then mix in the strawberry puree, vanilla extract, and a pinch of salt. Beat until the frosting is light and fluffy. Adjust sweetness or thickness by adding more powdered sugar if necessary.

Frost & Garnish:
Once the cupcakes are completely cool, frost them with the strawberry buttercream. For an extra burst of freshness, top with diced fresh strawberries.