Preheat oven to 350°F (180°C)
Combine all-purpose flour, baking soda, baking powder, and salt in a bowl.
In a separate bowl, cream butter and granulated sugar until light and fluffy.
Beat in egg whites one at a time, then stir in vanilla extract and milk.
Gradually mix in the dry ingredients until smooth.

Pour batter into a greased/floured 9-inch springform pan and bake for 35 minutes.
Let cake cool completely before slicing into cubes.
Mash 2 cups strawberries in a saucepan, add granulated sugar and lemon juice. Simmer until thickened (about 10-15 minutes), then cool.
Chill cubes on a wire rack to firm up (optional).
Whip heavy cream with powdered sugar until stiff peaks form.
Layer trifle in a clear glass dish: cake cubes, strawberry puree, whipped cream. Repeat layers.
Top with whole strawberries and refrigerate for at least 30 minutes before serving.