01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper and lightly grease the surface.
02 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl until thoroughly combined.
03 - Beat softened butter and granulated sugar in a large bowl until light and fluffy. Add eggs one at a time, mixing well after each addition, then stir in vanilla extract.
04 - Alternate adding dry ingredients and milk to the butter mixture, beginning and ending with flour. Mix until just incorporated, taking care not to overmix.
05 - Spread batter evenly in prepared pan. Bake for 22-25 minutes until a toothpick inserted in the center comes out clean. Cool completely in pan on wire rack.
06 - Combine sliced strawberries, granulated sugar, and lemon juice in a bowl. Let stand for at least 20 minutes to release juices.
07 - Whip cold heavy cream, powdered sugar, and vanilla extract until medium-stiff peaks form.
08 - Spread whipped cream evenly over cooled cake. Top with macerated strawberries and their juices. Slice and serve immediately, or refrigerate until serving time.