Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the mashed strawberries.
Pour the batter into the prepared cake pan and spread it evenly.
Bake for 30 minutes or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.