Combine softened butter and granulated sugar in a mixing bowl, ensuring a smooth mixture.

Add the egg and vanilla extract into the mixture, blending until thoroughly integrated.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt.

Gradually add the dry ingredients into the wet ingredients, stirring until a dough forms.

Gently fold in the diced strawberries.

Divide the dough into even portions and shape them into round cookies.

Arrange the cookies on a baking sheet lined with parchment paper.

Place the cookies in the refrigerator for 30 minutes to firm them up.

In the meantime, preheat your oven to 180°C (350°F).

Bake the chilled cookies for approximately 12-15 minutes, or until the edges turn lightly golden.

Allow the cookies to cool on a wire rack before serving.