Prepare the Cupcakes:

1. Preheat oven to 350°F (175°C) and line a cupcake tin with paper liners.
2. In a bowl, whisk together flour, baking powder, and salt. Set aside.
3. In a separate bowl, cream butter and sugar until light and fluffy.
4. Add eggs one at a time, mixing well after each addition. Stir in vanilla extract.
5. Alternate adding the flour mixture and milk to the butter mixture, beginning and ending with flour. Mix until just combined.
6. Divide batter evenly among cupcake liners.
7. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let cool completely.

Prepare the Strawberry Filling:

1. In a small bowl, combine diced strawberries, sugar, and lemon juice.
2. Let sit for 10 minutes to allow the flavors to meld.

Make the Whipped Cream:

1. In a chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract until soft peaks form.

Assemble the Cupcakes:

1. Use a spoon or cupcake corer to create a small well in each cupcake.
2. Fill the center with the fresh strawberry mixture.
3. Pipe a swirl of whipped cream on top.
4. Garnish with a fresh strawberry slice for a beautiful finish.