Preheat oven to 350 degrees F. Lightly grease or vegetable spray a 9 x 13-inch cake pan. Place the butter and sugar in a bowl and beat until well combined. Beat in the eggs one at a time. Mix in the lemon zest, extract, lemon juice and milk. In another bowl, whisk together the flour, baking powder and salt. Gradually mix the dry ingredients into wet ingredients until just combined. Spoon the batter into pan. Bake for 30 minutes, or until a toothpick inserted into the centre of the cake pulls out clean. Cool cake on baking rack. Slice strawberries and place in a bowl. Mix in the icing sugar and mint. Cut the cake into squares. Place on plates. Top with a dollop of whipping cream and spoonful of sliced strawberries.