01 -  Preheat oven to 175°C (350°F). Grease and line a 23×33 cm (9×13 inch) sheet cake pan with parchment paper. 
 02 -  In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. 
 03 -  In a large bowl, beat the butter and sugar until light and fluffy, about 3–4 minutes. 
 04 -  Add eggs one at a time, beating well after each. Stir in the vanilla. 
 05 -  Alternate adding dry ingredients and buttermilk, beginning and ending with flour. Mix until just combined. 
 06 -  Pour the batter into the prepared pan and smooth the top. Bake for 28–32 minutes, or until a toothpick inserted in the center comes out clean. Cool completely in the pan. 
 07 -  Toss sliced strawberries with sugar and lemon juice. Let sit for 30–60 minutes to release juices. 
 08 -  In a chilled bowl, beat heavy cream with powdered sugar and vanilla until medium-stiff peaks form. 
 09 -  Spread whipped cream evenly over the cooled cake. Spoon macerated strawberries on top just before serving.