01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper and lightly grease with cooking spray or butter.
02 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl until well blended.
03 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, approximately 3-4 minutes.
04 - Beat in eggs one at a time, fully incorporating each before adding the next. Mix in vanilla extract.
05 - Alternately add dry ingredients and milk to butter mixture, beginning and ending with flour. Mix until just combined, being careful not to overmix.
06 - Spread batter evenly in prepared pan. Bake 22-25 minutes until golden and a wooden toothpick inserted in center comes out clean. Cool completely in pan on wire rack.
07 - Toss sliced strawberries with granulated sugar and lemon juice. Let stand at room temperature for at least 20 minutes, stirring occasionally, until berries release their juices.
08 - Whip cold heavy cream, powdered sugar, and vanilla extract in a chilled bowl until medium-stiff peaks form, approximately 3-4 minutes.
09 - Spread whipped cream evenly over completely cooled cake. Arrange macerated strawberries over cream, drizzling with accumulated juices. Slice and serve immediately or refrigerate until serving.